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Fenris is back after a long while... with a new plan!
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Fenris



Joined: Jul 30, 2008
Posts: 145
Location: Horbury. UK
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PostPosted: Thu Sep 24, 2015 2:22 am    Post subject: Fenris is back after a long while... with a new plan!
Subject description: sequencer design and 808 drum circuits?
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Hello all

I hope this is the right place for this. As in the heading I have been away for a while due to RL being particularly nasty as regards my wifes health closely followed by me starting to suffer daily migraines for which the medication I take means I have to pick my moments. Basically when I'm not away with the fairies or ferrying wifey to Drs and hospital appointments.

My original plans when joining here was to go down the route of MFOS building. Bu other than a neat WSG I built at the time my dreams of synth building had to be down scaled due to the above plus fiscal complications Sad

Any way enough waffle and get on before the meds cross my eyes Very Happy

I've been ploughing through the forum for a week or so looking for a simple project to keep me sane. Also it has to be based on components I have in my 'pre-disaster' collection.

So I can build a 4017 sequencer with pulse and AND gate outputs. This can be used to drive some 808 based drum circuits. I have the chips for these and anything else I need wont damage the wallet at this sensitive time.

I also have a cordless drill case 'empty' that may be able to contain the circuits 'possibly'. It depends how out of hand this gets Shocked

The sequencer at this moment is only a schematic. At this point it uses 4 4017 chips paired by half a 4066 chip and half a 4013 chip. the plan is to run 2 banks of 16 outputs. 1 set dedicated to drum circuits the other to a couple of VCO/LFO type stuff to make noises with....I think Confused

The 808 drum circuits. Here I need a little help. I don't know which to use and how many. Also as I've read about them, specifically the clone circuits, I see some have trigger and accent inputs. Although in certain cases I see these have been joined together I think I understand that the accent could be connected to a CV output as well as the trigger line just being fitted to the trigger. Is this correct?

That info plus the number of drum circuits will determine the number of Outputs per channel and or number of CV outs. Any hoo my head is starting to slip sideways so heres the basic schematic. It is not complete but more a proof of concepet. The top half is the drum circut with its and gates and the trigger. The lower will become the synth side possibly.

The cyclic control is based on the 3 x 8 sequencer switching circuit as used by..........i'll credit later when I can remember Rolling Eyes

coments welcome on this ludicrous idea

Fen

PS ignore odd compnt vaues. I had to lie to the software to run the sim.


Circuit_Wizard_-_sequencer_switch_good.pdf
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proof of concept........

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 Filename:  Circuit_Wizard_-_sequencer_switch_good.pdf
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Fenris



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PostPosted: Fri Sep 25, 2015 1:24 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello there

I've been beavering away with the 'design' of this sequencer and have now come up with a 3X16 design. I know I must be mental!

The block switcher (left hand side of image) I saw on a post by KRS1972. This can be set to run the 1st and 2nd pairs of 4017s for a total of 32 steps. Or for all 3 pairs to run for a total of 48 steps. At the moment I have the control logic done (took me ages to get it working due to clinical stupidity)

Of note if anyone tries this pin 9 on each second 4017 needs a diode going to the diode of the reset line to prevent power being pumped into pin 9.

Things to ponder: Each pair could have independent step range control. Also each pair could be switched to run in sync rather than in sequence.

Also for reference is an image of a 16 step circuit. It seems newcomers get hung up on trying to go from 8/10 to a 16 step 4017. I remember going slightly nuts myself, many moons ago, trying to expand a circuit to some stupid size for a knight rider light effect. IIRC it needed 6 4017s. 3 to run up and 3 to run down, the outputs were paired using diodes. The logic control for this was four diode AND gates.

The other logic controls often seen to cascade multiple 4017s uses a, for example, CD4081 quad AND gate IC. One gate used for every additional 4017.

On this set of designs I use a transistor AND gate. Why? well it's easier to fit in the circuit 'real'. A CD4081 would be a waste for just a single pair and routing a PCB with more pairs I fear would get complicated. Laughing

The diode AND gate is also small and easy to fit in, BUT, it makes my head hurt. Looking at the schematic for it, and even though I know it works, it makes my head hurt because it just looks 'wrong' in a counter intuitive way. Surprised

Transistor AND gates are easier to understand and don't make my head hurt and they too work. Razz

4017 ICs, when turned on, can start at any where in the sequence because as the power levels up the 'noise' it makes causes the count to advance. So observe the capacitor resistor power on reset combo. a 10uF electrolytic and a 33/47K resistor holds the reset HIGH for around 1/2 a second which is long enough for the power fluctuations to pass. The reset then goes low and the count begins at the clock signal.

Note I have note shown decoupling caps. One, ceramic/poly, for each IC across the supply lines, close to the IC, keeps things clean of electrical noise that could 'clock' the 4017.

Fen


CD4017 3X16.png
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Runs 32 or 48 steps as is
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CD4017 3X16.png



CD4017 x2 Sequencer.png
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The basic 16 step setup.
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CD4017 x2 Sequencer.png



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Fenris



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PostPosted: Sun Sep 27, 2015 1:02 am    Post subject:  
Subject description: More Madness!
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Hello there

Well I have started to draw up a PCB. To keep it simple each pair of 4017 will be on its own board each board will be complete in it's own right. Each board can be run as a solo 16 step sequencer and only requires the addition of the diodes to steer the reset function to the 'switcher'.

That's the current idea anyway. Also to keep each board as small as possible the transistor outputs will be on their own PCB Shocked It's getting out of hand already! My only thought is whether to have these set as 1 x 16 or 2 x 8 or indeed 2 1 x 8 boards.

At this point I'm drawing and changing on the fly. The sequencer PCBs will, in theory, be able to be stacked using solid core wire to link the common reset lines and the power on reset components line (not shown). I love the 4017 chip. I've had hours of fun knocking up light chaser circuits with them. BUT my one bug bear.......... Why didn't the chips designers have the outputs in sequential order? I may waste a little board space running links and pads to have the outputs in order. At least that way the inter wiring should stay neat. Here's a pic of the small progress so far.

Fen


3x16Seq.jpg
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1 x 16 PCB
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3x16Seq.jpg



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PHOBoS



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PostPosted: Sun Sep 27, 2015 5:23 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
Also as I've read about them, specifically the clone circuits, I see some have trigger and accent inputs. Although in certain cases I see these have been joined together I think I understand that the accent could be connected to a CV output as well as the trigger line just being fitted to the trigger. Is this correct?
I've only build the cowbell and the accent is just another trigger input.

I'd personally use AND gates instead of the 4066 since you're working with digital signals only.

Quote:
Why didn't the chips designers have the outputs in sequential order?
yeah what's up with that, it's something that has annoyed me with a bunch of chips, it probably has something to do with the manufactoring process I guess.

Have you tested the circuit on breadboard ? I have had some troubles with the 4017 not working as I expected before.

Popcorn time

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Fenris



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PostPosted: Sun Sep 27, 2015 10:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi PHOBos Very Happy

Apparently you can never have enough cowbells! Laughing

Curious about the accent. I'd seen in the posts by -minus- that although there are both trigger and accent inputs they had ended up either tying one high leaving only one line as the trigger or both had been tied together and used as the trigger.

Good call on AND gates. I've drawn and run that in 'sim' so that'll be the first of many changes I guess Shocked

I've breadboarded 4017 circuits, and others, lots of times and other than 'user' errors I've not had any issue so far. The best user error ever was when I had just bought my first breadboard.

It was 3 boards held in a blue base. Running along the top edge of the boards was a power rail board two holes wide by enough holes to match the 3 boards it was attached to. My first setup was a voice chopper.

I built the preamp on the first board, the chopper on the second and the amplifier on the third. as each section was built I diligently fitted the +ve and -ve leads. I then spent 2 hours stripping it down and wondering why I was getting no chopped voice effect but could here local radio through the amplifier.

Eventually I noticed that the red and black strips on the power strip were different in what turned out to be ...... a quite important way Embarassed
The red line was one continuous line down the length of the strip. The black had two breaks in it's length. The black lines were the same length as each breadboard width...... I'll leave you to work out what that meant scratch

As regards breadboarding I have been warned that the boards themselves can have capacitive effects on circuits especially if running at higher frequencies.

Soooooo I only need to worry about a trigger circuit per 'drum' circuit.

Fen

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Fenris



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PostPosted: Mon Sep 28, 2015 2:05 pm    Post subject:
Subject description: PCB variant mobius. The OCD edition!
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Hello there

still doodling the PCB. Currently this iteration has the outputs of the 4017 jumpered into sequential order. It's just one of my 'things' as regards the pins of the 4017 Laughing

once I'm sure I have the PCB setup correctly, re stacking, I'll draw up the trigger bank. Quantity per board unknown. The figure is dependent on how many drum circuits I want to run at once.......

At some point I'm going to see if I can modify the makita drill case. Its a blown molding, I believe is the term. The outer shell and the interior shell are one for both halves. So theory is I use a blade to cut around the inner edge and the inner will separate leaving me with a possible enclosure.

Obviously the two halves may become a bit flexible but a some sort of beading fitted around the edges will stiffen them and act as a mounting point for the panels.

fen


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PostPosted: Mon Sep 28, 2015 3:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

Time is short and I need to go back and re-read everything, but as for 808 voice circuits and trigger/accent inputs, it's usually easiest to just tie them together for simple stuff.

Note that if you want to feed CV to the accent, it expects a minimum of 4V and typical max of 14V so you might want to feed whatever CV in (assuming 0V -> whatever) to an offset of 4 or 5V to get it to behave as you'd like.
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Fenris



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PostPosted: Tue Sep 29, 2015 2:15 pm    Post subject:
Subject description: The madness continues!
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Hello there

Thanks for the heads up elmegil. I've tweaked the CV pots with a change in resistor value on the wiper and the addition of a resistor ground side. Theoretically the values changed/added give me a 4.2V to 14.5V range.

I'll have a play on a breadboard at some point and see what transpires. That said I've doodled the schematic a bit more adding the CV out circuit and the trigger circuit. So the first irritant occurs..........

The CV out is a dual rail affair......... everything else is single rail. My understanding of op-amp design breaks down here in as much as I would like to change the CV circuit, circled in red, from dual rail to single rail can any kind soul help please? It's not for want of trying on my part but as much as I have read googled etc etc I lack the wit to do it Crying or Very sad

Also drawn up is the PCB for the sequence switcher. A 4017 and a 4081 plus one resistor on board.

here's the pics!

Fen


seqswitch.jpg
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Switcher PCB
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seqswitch.jpg



Circuit_Wizard_-_sequencer_switch_good3.pdf
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schematic only one bank of outputs shown.

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 Filename:  Circuit_Wizard_-_sequencer_switch_good3.pdf
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Fenris



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PostPosted: Sat Oct 03, 2015 12:00 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello there

Not much to show at the moment. Sorted out the dual rail to single rail CV side of things. Then refined it some more, thanks to input from PHOBos, CHEERS!

EDIT: I just realised I am an idiot of the first order.... the trigger circuit is also dual rail so I may as well have the CV as dual rail and have all the triggers and CV paired on one board powered by dual supply DOH! The CV still benefits from Master PHBos's input though Very Happy

So at the moment I have a single PCB (16step) designed to build up to 3 banks (in theory more). Now my next technical question is.............

If I'm using 12V - 15V Dual rail supply. Obviously the sequencer will sit at +VE and GND whilst the drum circuits are dual rail. What can I have in terms of number of outputs from one sequencer module.

That is, currently I have one CV out and one trigger, this would go to one drum circuit. How many more CV out and trigger pairs could I reasonably add to one sequencer module?

Fen (rapidly going maaaaaaad!)

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PostPosted: Sat Oct 03, 2015 4:50 am    Post subject: Reply with quote  Mark this post and the followings unread

hello there

Further to the above. I've had a little play in sim. To the far left of the image is the transistor pair that is the stock input for the 808 circuits. top line being accent from the CV lower line being trigger.

I think accent may also be known as velocity? If a pieo sensor and circuit were used as input.

The fisrt 8 CV pots go from 100% - 65% (there is a deadone from 100% to 95%)

EDIT: its not dead theres an extra pulse at the start of cycle so 17 instead of 16.... PHOBos had that problem to.......where did I see that?

the second 8 CV pots go from 35% - 0% ordinarily you would see a regular step down like a staircase. but because the accent IN and Trigger IN are bound together by the transistor switch you get the decreasing spikes instead.

I presume the 808 circuits could also be played if interfaced with a pieo sensor circuit you could have a drum synth kit.

excuse the spelling of pieo the _ key on my keyboard is dead.

fen


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Spikes!
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PostPosted: Sat Oct 03, 2015 6:07 am    Post subject: Reply with quote  Mark this post and the followings unread

http://www.electro-music.com/forum/post-402866.html#402866
I think there's another thread where I ran into the same problem, reducing the pulldown to reset solved that.
(the little gate also had some similar problems)

and here are some z's for you to use:
z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z
let me know if you run out, I have more where those came from Wink

edit: oh an extra pulse not skipping,. maybe this one ?
http://electro-music.com/forum/post-398500.html#398500

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Fenris



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PostPosted: Sat Oct 03, 2015 9:23 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello there

Cheers PHOBos. I knew I'd seen it mentioned! A search also brought it up as a standard issue it seems. I'm trying to recall if I ever had an issue with LED sequencers but I'm pretty sure I had no issue.

Though that begs the question does the differing end use have an effect? Can't see it but who knows?

I know the software I use is only indicative not accurate. I've done an overlay of the CV steps on the CV/trigger spikes the first (extra spike) occurs on the CV rising edge the last spike occurs on the CV falling edge and the intermediate spikes are at the end of each step. Thats in the first 4017.

The second 4017 spikes all sit center of each CV step which seems more normal. I tried using a transistor on the clock line and this fixed the first 4017 group but then the second 4017 group drifted late and the extra pulse occurred in that group instead Shocked

I really will have to bread board the basic 16 step sequencer and see what occurs. Duly noted the links provided thank you.

What are your thoughts on the loading on the outputs in terms of how far can you go? So how many drum type circuits could I possibly drive maximum?

Piezo...... Piezo, Piezo, Piezo!!!! Thanks for the zzzzzz's I can talk proper again innit!

Fen

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Fenris



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PostPosted: Sat Oct 03, 2015 3:03 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'm worried..................

Shhhhhhhhhhh. I think my laptop is, or at least the software is sentient.

After hours of fiddling around with pulse delay sub-circuits, components etc etc. All to no avail in getting rid of the extra pulse. It is now only doing it on the initial startup (in sim) all the following iterations have only 8 pulses per 4017......... I think the software worked out what I wanted and did it...........

That said I am on new meds for chronic migraine but I'm damn sure it was having the extra spike on all previous runs. Honest o_O

Fen (Terminally Bemused)

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PostPosted: Sat Oct 03, 2015 5:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

Fenris wrote:
What are your thoughts on the loading on the outputs in terms of how far can you go? So how many drum type circuits could I possibly drive maximum?

depends on what you are driving it with and the input impedance of the 808 circuits.
with the transistors on the outputs you'll probably can drive a lot of them, straight from CMOS not so many,
better to add some buffers to that anyway. (voltage follower is also very useful for that)

and here's another 16 step that might save you some trouble:
http://electro-music.com/forum/post-404558.html#404558
of course you would have to start over with the PCB design.

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PostPosted: Sun Oct 04, 2015 1:54 am    Post subject: Reply with quote  Mark this post and the followings unread

LOL! This is getting out of hand I fear!

OK so I need to work backwards. what drums do I want (all of them)

Cymbal, Hi-hat open, Hi-hat closed, Kick drum, Snare, Tom (more than one?)

I think patchable to chop and change. I can start small build up.

SO the sequencer. Will need a gate and trigger per drum unit added.

Voltage followers Do I need a voltage follower per output per drum unit?

or diode the outputs to a follower per drum unit.

other than that. the thought occurs.... I have a bucket load of 4017s. Make one 16 step sequencer per drum running from a common clock or pairs of drums on one stepper to spread the load............

lawks I feel like I'm right back at the beginning......aged 14 armed with a 36Watt iron (dad gave me) wondering why nothing works Laughing

fen

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PostPosted: Sun Oct 04, 2015 3:27 am    Post subject: Reply with quote  Mark this post and the followings unread

Fenris wrote:
Voltage followers Do I need a voltage follower per output per drum unit?

That would be 1 for every sequencer output with which you could drive more than 1 drum unit (of course if you connect
more than 1 they do the same thing). But I think for drums a transister output might actually be easier and work great.
I often prefer voltage followers because they can provide both a positive and negative voltage (negative could also be 0V)
while transistors (when used as a switch) can only provide one of the two. They are most useful for analog though and since
your trigger outputs are just on/off and you only need a positive voltage transistors would probably be the prefered choice.
They can also drive much more than a standard opamp. However keep in mind that transistors don't have a short circuit
protection so I'd put a small resistor in series with the ouput.

Quote:
Make one 16 step sequencer per drum running from a common clock or pairs of drums on one stepper to spread the load............

One per drum, this makes it possible to clock from different sources (maybe something like a divider, or swing generator)
and you can get much more interesting rhythms by using a different number of steps for each sequencer (I like primes).
So just start with 1 16 step sequencer and than you can build more of them later on, you might also come up with some
new ideas after you've made the first one.

btw I've had it happen more than once where I was almost done with the design and than came up with a different
way to do it and had to start over from scratch.

Here's some music to listen to while you think about it:
https://www.youtube.com/watch?v=conwt8Dy27Y&list=PL359FFEB4FDC11841 banana

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Fenris



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PostPosted: Wed Oct 14, 2015 2:44 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello there

Oh my lots to think on.... sadly little head room to think with. Mr Migraine took advantage of my medication change to move in for a week! and have sole occupancy. Hell I really wanted to put my head through the wall! Still I survived thanks to my dear wifes support and tender ministrations Smile

Now then! Yep lots to think on. Good bit of music to! I'm still playing around with the sequencer circuit.......... GRRRR! But actual construction will have to wait a bit, though breadboarding the CMOS can be done. Getting carried away I forgot that 16 pots and switches are just hellish expensive with the fiscal issues we're in at the moment. But they are on my Xmas present list Very Happy In fact they are the only thing on my list!

So Plan A is I have all the parts to build a sound card oscilloscope which though limited will be of some use. It will go well with my DIY TTL/CMOS logic probe.

I have only to pick which drum circuit to build to use as the test driven circuit for when the synth is built/breadboarded for testing. I may go CH/OH as it's 2 for one Very Happy

Other than that here's an idea I had. Useful or no I know not, I also suspect it's nothing new. When Cascading 4017 IC's the most common method seems to involve losing output 0 to the required driving logic and because these go live a bit before they are used in the flow of sequential outputs.

So why not use a pair of AND gates on output 0 of each 4017. See attached image. Basically you can use output 0 as normal via the output of the AND gate. The first OUT in a sequence will be on as it should be.

All other AND gates are off until required by the relevant output 0 and inhibit line both being logic 1. So where as you may usually lose output 0 and 9 to the driving logic of cascading you can reclaim output 0 at least.

It may also not suit some circuit designs. It can preclude doing things in certain ways or just foul up the logic in unexpected ways in certain circumstances.

My only other 'thing' is. Although I don't trust the sim software as far as I can throw it 'real world testing is the only proof' in sim the standard cascade methods show a bit of a pause between 1st and last outputs and intermediate pairs..... propagation delay I think it's called? OK it's in milliseconds I really should get a life. But the AND gate method seems to severely reduce the effect..........



Other than that it could just be the software handling the circuit better in one method than it does the other. Remember...... I actually know BUGGER ALL Very Happy

Here's some music for your consideration (Damn you Stephen Fry Smile )

https://www.youtube.com/watch?v=ulDQdikjSSE

Fen
[/url]


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PostPosted: Fri Oct 16, 2015 12:39 pm    Post subject:
Subject description: Filling an empty head!
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hello there

well it's day four and no migraine or even a hint of one......shhhhh!

with this clear headedness I can at last string coherent thoughts together for long periods of time. We're talking DAYS!

Anyway here goes. I've been 'designing', in the loosest sense of the word my modular drum sequencer. Despite the corporeal build delay I will be able to test the cmos core of the theoretical circuit I've cobbled together from disparate parts gleaned from posts all over the web.

But mainly here, MFOS, and a randomly stumbled upon PE sequencer PDF scanned document.

So the core circuit is a pair of CD4017, One CD4081 and a CD4001. With these chips I can run a 1 x 16 or, at the flick of a switch, 2 x 8 sequencers.

Primarily the above is taken from the Practical Electronics March 1979 Sequencer project. Although it has to be said, and it looks like some scribbles on the scans indicate, there is an error in the latch logic of the schematic that bugger up an otherwise neat idea. I don't know if the PCB patterns have the same error but I'm rolling my own anyway......well I will be and my output interface is totally different anyway.

That said I worked out how to get the latch logic sorted so that you could actually switch between 1 x 16 or 2 x 8. in 2 x 8 mode each 4017 can have it's own clock drive.

After that I pulled all the disparate parts of the output interface together. To match one CD4017 I need 2 CD4081 IC's to form the pulse OUT in conjunction with a gate to trigger circuit.

To each OUT of the 4081 a switch and pot for CV. Also here a tap out for an LED on each OUT for indication when sequencing. On the OUT of each pot a signal diode. These are then summed into what is the MFOS drum trigger circuit.

On Rays site this is shown with a piezo on the input. The circuit is divided into two parts. The first half outputs a CV output. For synth drums I understand this is termed velocity. The harder the piezo is struck the greater the initial voltage level the softer the lower the level. This effects the apparent sound of the synth drum. The other half of the circuit provides the trigger, a 5V pulse commonly, though some units vary in requirement.

Thats it up to that point. There is some finessing to do and some ideas bubbling under. Today I also etched and drilled my first PCB in ages, for the sound card oscilloscope. good fun!

Here's a pic of the output circuit to give you the idea and a pic of the PCB I've just done. Toner transfer method FTW!

Fen


Sequencer Drum Interface.jpg
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2015-10-16 17.28.52.jpg
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2015-10-16 17.30.49.jpg
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I had to cut the eyes off the pins on both!
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PostPosted: Sat Oct 17, 2015 7:54 am    Post subject: The PE Sequencer Core Corrections
Subject description: Practical Electronics Sequencer March 1979
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Hello there

As mentioned previously. The core of my proposed sequencer has come from the PE sequencer. Also as mentioned I had to correct the schematic for it to work.

Now the correction was only partial it turns out. Everything still works but I spotted a further error in the same area. Its not major but having had a brief look I do believe the error may have made it onto the PCB patterns in the PDF scan.

At this juncture I will say I am quite prepared to be called out if I have got any part of this wrong. I have only run the corrected circuit in a simulator both as it was and now how it is. One works..... The other doesn't.

So basically if you look at the main picture. You can see that there are a few red circles on the page. This is me denoting errors. The primary error is the CD4016. It is erroneously connected to the mode switch line. In this state it fails to function in 1 x 16 mode as it never gets a logic 1 EVER.

What is supposed to happen is when IC6 is running its CD4016 Switch closes so its summed outputs are passed out. When IC6 resets at the end of its run, its CD4016 opens and the sequence continues on IC7 whos CD4016 switch has also closed so the summed outputs can be passed out.

The cycle loops round continuously of course. The only time IC7s CD4016 switch will close is when you switch modes to 2 x 8. In the mode both CD4016 switches close and both 4017 ICs run (They can be clocked independently).

You can see in the smaller image a red line now goes from the effected CD4016 to the Steering diode above it. This is the only connection between the switch and the diode.

Initially I had removed the mode line between the IC10d pin 13 and IC4d pin 12. electing to hold pin 12 and its fellow pin 9 high to maintain reset functionality in both modes. So at that point I now had both modes working and reset operated in both (initially it didn't after the mode line removal)

Things took a slight down turn when I realised that I could reinstate the mode line. But then the reset went wyrd (in an old english sort of way) Which brings me to the other red circles. These are the logic controls to the enables and reset pins of both 4017 ICs. To get these to work again basically the lines marked to go to pins 15 and 13 circled in red should be transposed to 13 and 15 (same ICs just change the pin destination).

RED DIODES: Hmmm. OK this is me. In the sim software without these even with the faults fixed things don't work properly. All the positive voltage seems to shoot into the outputs of the NAND gates stopping the 4016 switches closing and stopping the change over latch working. In real life This probably wouldn't happen. but to get things to work in sim and prove the faults fixed I had to drop them in. Other than that I'm wary of throwing INPUT voltages (12V in this case) into OUTPUT terminations. If any one has wise words as regards this please say!

Then everything works lovely.

Note I am note sure on copy write so I am only posting the page of the schematic for reference in case anyone out there finds the PDF scan for themselves and wishes to give it a bash. Hopefully they see this before trying it out though :/

Fen

.


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PostPosted: Mon Oct 19, 2015 2:06 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi there

Well I've been busy. Hope to finish my soundcard oscilloscope today (boxed). Then just need to make my own leads.

I've been drawing up my own schematic for the sequencer core. Basically it's the PE core with a couple a bits added on to switch the output circuits from singular to dual function.

I hope to breadboard this very soon. At least then I can see what happens with the extra diodes not present in real life

Then of course I can use the o'scope to look at all the pretty pulses Very Happy

The switched sockets on the 'reset at' line have me a little perplexed. If I plug a line in to go trigger something else this breaks the line to IC1 (or2's) own reset. How does that work?? What am I missing??

Any hoo Pics.


2015-10-17 17.08.34.jpg
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Nearly there
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PostPosted: Tue Oct 20, 2015 2:51 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello there

Not much going on today. Father in laws weekly visit takes precedence. But yesterday I boxed my oscilloscope interface. It took all day! Not perfect but it does and I can fettle it later.

I have only to knock up some 10x Probes and the jobs a good 'un. The unit passed it's 'Burp' test as per the documentation and I just have to do the final LED limit threshold adjustment. Basically if the input is approaching the sound cards input limit the LED on either, or both channels lights up as a warning.

I did manage to plug an arduino circuit into it as a test. The arduino is driving a 4 x 5 LED matrix in a pseudo random pattern (The code was done for me. I am just not capable Sad ) . So I took line from one LED to the scope input and a shared GND and watched XOSCOPE monitor the input.

Yep. A bit rough with 2 wires as the link but it works!

Fen


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PostPosted: Tue Oct 20, 2015 8:01 am    Post subject: Reply with quote  Mark this post and the followings unread

that looks great! Very Happy
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Fenris



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PostPosted: Wed Oct 21, 2015 11:18 am    Post subject: Reply with quote  Mark this post and the followings unread

Cheers PHOBos

Praise indeed coming from yourself Smile

Finished it completely today. The case is a 'PSU' block. So there is a 25 x 30mm rectangular hole at one end and a small 8 x 8mm hole at the other.

But first things first. I made my second 10x probe. Basically a 6.8M and a 2.2M resistor in series to make a 9M. They are laid in tandem and the leads at the same end bent over to each other, soldered and trimmed. This is then slipped into a bit of heat shrink leaving the remaining leads clear at one end.

One of the leads is then bent back up the covered resistors. A 5.6pF ceramic cap, nearest to 6pF I could get, is laid on top of the resistors with one of its legs bent up in the direction of the resistors. So you have a resistor lead and capacitor lead in one direction and a pair in the other.

I spiral wound each cap lead round each resistor lead and snip off the access. A biro tip is used to make the probe tip. This is heated with the iron to boil the ink out of it then filled with solder prior to soldering one end of the resistor cap package into it.

After that its fit the coax through the pen body. fit a wire for the ground also. Trim the outer insulation exposing the shield, gather into a tail and solder. attach the hookup wire to this. Trim the core insulation twist and solder the wire and solder the tip/resistor/cap package to this. Rebuild pen body around this. Solder alligator clip to hookup wire and your done.

Now the holes in the case. A black ice cream tub! cut up to fit the rabbat in the larger hole and the smaller hole has a piece hot glued inside, having been prepped for the audio out cable to pass through. This leaves an 8 x 8mm hole about 3mm deep. I filled this with hot glue which acts as a grommet for the wire and makes it look neat!

The unit also had its limit LED level adjusted using a meter on the wiper of the internal adjuster. Both leads have been plugged in and used in tandem and it works fine. So far on square wave pulses available but it was enough to see it working.

Now I promise to get back on with some sequencer and drum type stuff. I'm warmed up and my head is still clear (barring a small dose yesterday) NEXT!

Fen


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PostPosted: Fri Oct 23, 2015 2:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello Chaps

Well I think the game plan is forming a more coherent path. Last night I finished boxing a logic probe I made a few years ago. This will be good for testing logic states around the sequencer core of course.

The on to the plan.

Bread boarding the sequencer core (yay) hopefully today. If not at least clearing the board and plugging the chips in.

Things in the pipe line - Drawn up a PCB of the MFOS drum trigger. This will be useful to test the 808 circuits as they are done.

Ripped open a 12V 1A DC wall wart for its transformer. This will become the 12V AC supply for the 12V bipolar supply ala MFOS stylee. PLEASE DO NOT DO THIS IF YOU AREN'T MAINS CONFIDENT! I've had a few years under my belt and have never had an accident and despite this have never become complacent in the presence of mains (240V UK) voltage.

My intent is to draw up a bespoke PCB which will have the transformer on it with the requisite circuit to create the bipolar output. This will be housed in a plastic enclosure when finished. I realised late in the day I would need a Bi supply and I have the parts to do this.

Also to warm up my soldering skills, now my head is free of the migraine (shhh), I'm making a surf synth effect circuit for the wife to relax to. Her health is not robust and anything that helps has got to be a good thing.

more later

Fen

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PostPosted: Fri Oct 23, 2015 3:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hello there

Well the madness grows apace!

The bread board has been cleared and dusted 2 x 4017, 1 x 4001, 1 x 4011, 1 x 4081 have been plugged in. 4 x 1n poly caps, 8 x 100K res', 2 x 10K res', 4 x 1N4148 diodes have been gathered.

One bank of 8 red LEDs with flying wires has been made the other is in parts waiting assembly. These will be used to monitor what is happening in both modes.

The 4011 is what I will use to make the clocks (2x). So I can use one to drive both 4017 in 1 x 16 mode and the use one clock each in 2 x 8 mode at disparate rates if wished.

I've made one side of the 4011 up. Rather unscientifically I just grabbed the first google image for the circuit of the web. When fired up an LED I had put on the out put glowed steadily. I was pretty sure it was working but probably so fast as to appear stable.

This is where my newly boxed logic probe came in useful for its first official use. I attached it to +ve and -ve the probed the output. Sure enough the red and green LEDs lit up. Ordinarily these may alternate or one or the other may light depending on the presence of a logic high 1 or a logic low 0.

Or as in this instance both on (could indicate an open circuit) but the third LED (Amber) indicates when the logic state is rapidly switching between 1 and 0. In this case I'm pleased to say it lit up showing there was indeed a rapidly occurring clock pulse.

So all I have to do now is find a better set of values to bring the clock speeds down to more usable figure Very Happy

More on the morrow!

Fen


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