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This noob needs help
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fldrvr



Joined: Jul 13, 2006
Posts: 33
Location: USA

PostPosted: Thu Jul 13, 2006 1:34 pm    Post subject: This noob needs help Reply with quote  Mark this post and the followings unread

Hey all good to meetcha!

I've already posted these questions on the EA forums, so please forgive me, but I'd like to get as many points of view as possible..

http://www.getlofi.com/2006/02/4093-based-oscillator.html

I'm thinking pot instead of photocells. So, to make the frequency go higher, do I connect the input (pins 1, 6, 9, 12, right?) to the wiper, or is it the otherway around (outputs 3,4,10,11, right? )

Also, do you think a resistor/ LED combo instead of diodes will affect the sound (higher/lower pitch? anything else?) someone did respond about the difference in forward voltage, but i don't nderstand that particular bit.

Is there any other way to do those outputs without diodes? He mentions using a quad op amp voltage follower instead of diodes. On another forum (thereminworld) I saw someone suggest an op-amp summer. What would be better/ what's the difference? The voltage follower seems simpler. I'm assuming that each output goes into an individual part of the opamp?


another question- I've got a bunch of mps a27 darlington NPN transistors, and some tip32 pnp transistors. The tip32 looks different, it's bigger and has got one of those little metal tabs on the top. Also, my understanding is that the darlington is like 2 transistors in one.
My question is, can I use those two to create this circuit?

http://www.geocities.com/SoHo/Lofts/8713/optotheremin.html

Thanks all in advance for your comments! If you've seen this already, sorry!
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zipzap



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PostPosted: Thu Jul 13, 2006 4:48 pm    Post subject: Reply with quote  Mark this post and the followings unread

I´m going to bed now, so i won´t answer that first question, but if you like to start doing something build that theremin. It looks simple, and that has often been a hint to me that almost any transistor can be used. Use the Darlingtons like they were a single (strong) transistor. Have Fun!
If it doesn´t work double check every connection, if it still doesn´t ask again cause maybe i´m telling crap here...
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zipzap



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PostPosted: Thu Jul 13, 2006 4:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

The pinout of those transistors you have may be different, look in the datasheets. Also maybe you have to use a slightly higher or lower cab, depending on the ldr. And welcome! BTW, I alway ask at least two people if i really whant to know about something.
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Uncle Krunkus
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PostPosted: Fri Jul 14, 2006 4:28 am    Post subject: Reply with quote  Mark this post and the followings unread

It doesn't matter which side goes to the wiper. The pot will give you a variable resistance as long as you use the wiper and one side, (which depends on how you want to turn it) so it is not polarised. As long as you go output to pot to input it'll be fine.
I'd start by using the diodes an then try out other ideas.
As for the theramin idea, try out your transistors, they might work (in some way) if they don't you're only looking at 50 cents for the 2N3904/6.

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zipzap



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PostPosted: Fri Jul 14, 2006 6:13 am    Post subject: Reply with quote  Mark this post and the followings unread

That theremin is the simplest oscillator i´ve ever seen. Anybody know what waveform it puts out? (my breadboard is too crowded right now, as you can probably imagine)
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fldrvr



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PostPosted: Fri Jul 14, 2006 6:59 am    Post subject: Reply with quote  Mark this post and the followings unread

The question about the pots, I had posted on another forum (EA) and someone replied that the frequency control would either produce higher freq or lower freq with the turn of the pot, depending on how it was wired (inputs or outputs) to the wiper.... I just was wondering if anyone knew which way would produce higher, which lower.

yeah, I'm sure that the diode thing is probably easiest... On Getlofi, I saw that with the Atari Joystick Synth, he used this circuit and pots, and he said he used 15k, I was wondering if higher values might be better (100k?)

Thanks all for your help! I'm definitely going to try that theremin also. I've got a crapload of the darlingtons and I have to figure out something to do with them.
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Uncle Krunkus
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PostPosted: Fri Jul 14, 2006 7:31 am    Post subject: Reply with quote  Mark this post and the followings unread

No, like I said, it doesn't matter whether the inputs or outputs go to the wiper. What matters is which of the outside terminals on the pot goes to the gate. One of them will mean the frequency will go up when you turn the pot clock wise, the other one means it will go up when it's turned anticlockwise.
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Uncle Krunkus
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PostPosted: Fri Jul 14, 2006 7:37 am    Post subject: Reply with quote  Mark this post and the followings unread

Changing the pots to 100K would lower the lowest pitch you could get out of each individual oscillator.
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fldrvr



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PostPosted: Fri Jul 14, 2006 9:53 am    Post subject: oooohhhhhhhhh....... Reply with quote  Mark this post and the followings unread

hey thanks unc! i wasn't getting it. I have as yet to invest in a breadboard, so i try to figure out as much as i can 'bout a circuit b4 i try and assemble.

I have a real noob question.... can i simply connect the grounds in the circuit to the neg terminal on the battery? is that enough? or do i need to put some shieling in the case, connect to that?

thanks again!
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zipzap



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PostPosted: Fri Jul 14, 2006 10:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Funny! When i started that was the one question i just couldn´t understand!
Yes! Ground and - of the battery are the same. In this case. There are circuits where you have +,-, and ground. Then ground will be in the middle, eg +12v, Ground (=0v) and -12v. Bit confusing, i know.
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fldrvr



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PostPosted: Fri Jul 14, 2006 10:33 am    Post subject: I got another one for ya zip Reply with quote  Mark this post and the followings unread

Thanks!

Now, let's say I want to build a 3 oscillator noisemaker, along the lines of what the 4093 is (each oscillator parallel then mixed at the end), but instead using three of the transistor theremin schem I posted above. That schem uses a 1.5 v power source. If I wanted to run all three oscillators from the same power source, could I just use 1 1.5? or would it be 3 (4.5v)? How would I wire that?

Also, would I need the diodes like in the 4093? Or just wire all three straight to the out?

Thanks for your help
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Uncle Krunkus
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PostPosted: Fri Jul 14, 2006 3:20 pm    Post subject: Reply with quote  Mark this post and the followings unread

They would each run off the same voltage. But together they would draw three times the current. (so your battery would die three times faster)
Mixing the three of them would be a bit more complicated. First, where the jack is you would need a cap in series for each one so that their DC voltages don't interfere with each other. (say about 1uF +ve side to the "theramin") Then the other sides of the caps would go to a summing amp (ie a 100-150K resistor in series with each output, then the other side of the resistors joined together and into an op amp with enough gain to bring it back to a line level)
That's a very simple explanation. As always, breadboard it first.

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zipzap



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PostPosted: Sat Jul 15, 2006 1:19 am    Post subject: Reply with quote  Mark this post and the followings unread

Know what, if it´s noise you´re after, then you might like this:
Instead of just mixing those 3 oscillators you build 4 and get a chip called 4070.
Wire like this:
Pin12, 13, 14 +
pin 7 -
osc 1-4 go to pin 1,2,5,6 (directly, no cab or diode, one by one, not all tied together)
Pin 3 to pin 8
pin 4 to pin 9
Listen to pin 10 you´ll like that, but watch out, it´s loud, so always turn your speaker down first!
You can also listen to Pin 3 (Trumpet) and 4 (Cello).
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dnny



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PostPosted: Tue Jul 18, 2006 12:11 am    Post subject: Reply with quote  Mark this post and the followings unread

zipzap wrote:
That theremin is the simplest oscillator i´ve ever seen. Anybody know what waveform it puts out?


here is a nice explication on how this circuit works

Nicolas Collins wrote:

This circuit oscillates because of the principle of argumentation. Each Inverter stage, puts out the opposite of whatever signal appears at the input: if binary "1" represented by 9 volts, is applied to the input, then a "0" (0 volts) is sent to the output. That 0 flows through the resistor back to the input and the whole process begins again, causing the circuit to flip back and forth between two stages, generating a square wave. The speed of the flip-flopping (the pich) depends on the values of the resistor and the capacitor. It's like the Monty Python argument, or a dispute in a bar: I disagree whit everything you say, so our output keeps flipping between yes and no according to how fast each of us can reply. The resistor and capacitor act like booze - the more you add the slower the argument goes, ergo the lover pich.


so square wave it is.

and remember that you can use any Schmitt Trigger (74C14, 4584, 40106, 4093)

HTH
daniel

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fldrvr



Joined: Jul 13, 2006
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PostPosted: Tue Jul 18, 2006 12:02 pm    Post subject: Thanks, but... Reply with quote  Mark this post and the followings unread

Thanks all for your comments, they were very enlightening. Now I've got further questions.

Well, since the 4093 we've been talking about here has four Schmitt triggers, I figured that I could build a Schmitt trigger with the transistors I wrote about earlier. So I found this Schem here:

http://www.play-hookey.com/digital/experiments/rtl_schmitt.html

I this the same as what one section of the 4093 is? could I then just connect a resistor from the "out" to the "in", and run the "in" with a cap to ground?

The other thing is, on the 4093 schem, each section has two pins going in to one out. The schem I put above only seems to indicate one "in". So I'm a bit confused there.

Anyhow, thanks again for all your help!
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dnny



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PostPosted: Wed Jul 19, 2006 1:09 am    Post subject: Re: Thanks, but... Reply with quote  Mark this post and the followings unread

fldrvr wrote:

Well, since the 4093 we've been talking about here has four Schmitt triggers, I figured that I could build a Schmitt trigger with the transistors I wrote about earlier. So I found this Schem...


IMO it's much more complicated to build it whit the transistors, and cost more (even if you had the trans)- so i would get the chip.

fldrvr wrote:
The other thing is, on the 4093 schem, each section has two pins going in to one out. The schem I put above only seems to indicate one "in". So I'm a bit confused there.

according to getlofi the inputs for 4093
are
1,5,8,12
outputs are
3,4,10,11

take a look on MFOS- Weird Sound Generator -it uses the same type of square wave osc's and is a good start for fun noise making

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chutneyfarmer



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PostPosted: Fri Jul 21, 2006 6:12 am    Post subject: any chance of a strip-board layout? Reply with quote  Mark this post and the followings unread

heya guys & girls

just registered, so hello Smile

i've been playing around with simple circuits over the last few months (light-sensitive theremins etc.) and am currently thinking of trying to build the circuit mentioned in the first post...

http://www.getlofi.com/2006/02/4093-based-oscillator.html

my only problem is that i'm still really bad at planning out stuff on strip boards. if someone would be able to draw out a simple strip-board layout for the circuit i'd be most greatful.

looking forward to posting more on the forum.

thanks,

gary
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Uncle Krunkus
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PostPosted: Fri Jul 21, 2006 7:51 am    Post subject: Reply with quote  Mark this post and the followings unread

It's getting way past my bedtime, but I'll see how I go over the next few days.
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zipzap



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PostPosted: Fri Jul 21, 2006 8:06 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi there
designing layouts...
This was always hard to get into for me. But if you start by drawing the chip on a piece of paper, with the stripes going from the pins, and just start with the closest components, trying to arrange them, you will find a solution. And soon you get some exercise and it becomes easy practice.
If you have many chips it helped for me to do this simple drawing with each of the chips. Just ic and the components around it. Then see how those little blocks can be arranged to make the easiest connection between them.
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zipzap



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PostPosted: Fri Jul 21, 2006 8:07 am    Post subject: Reply with quote  Mark this post and the followings unread

hey uncle, do you alway go to bed at 7:51 in the morning? Wink
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Uncle Krunkus
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PostPosted: Fri Jul 21, 2006 3:11 pm    Post subject: Reply with quote  Mark this post and the followings unread

No, it was about 1:30am when I posted that. Maybe somebody moved your house to Hawaii and you don't know about it yet! Laughing
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fldrvr



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PostPosted: Sat Jul 22, 2006 7:49 am    Post subject: Reply with quote  Mark this post and the followings unread

Hey all! thanks for your replies.

I've got two chips- one 14049 hex buffer and a 4096 (i don't know what it does). Any suggestions on how I can use these in a project? )any project(
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dnny



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PostPosted: Sat Jul 22, 2006 8:18 am    Post subject: Reply with quote  Mark this post and the followings unread

fldrvr wrote:
Hey all! thanks for your replies.

I've got two chips- one 14049 hex buffer and a 4096 (i don't know what it does). Any suggestions on how I can use these in a project? )any project(


4096 is a hex inverter (datasheet)
you could make 6 pre amp´s of this chip for electret microphone elements! or you could turn it to 3 Schmitt Triggers - look the datasheet for schematics...

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fldrvr



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PostPosted: Mon Jul 31, 2006 11:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Well I got another question now- what would happen if I applied a higher voltage to the transistor optotheremin from the schematic in previous posts? IT calls for 1.5v, what would happen if I applied 3V? or 4.5V?

Etc.

Thanks
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Uncle Krunkus
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PostPosted: Mon Jul 31, 2006 2:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

The main risk is that too much current will go through Q2. Try putting a 1-5K pot on Q2's Collector, Hook up your 4.5V and slowly reduce the resistance. I don't think Q1 will be a problem, as it probably never gets the chance to saturate, but I might be wrong. The resistor on Q2's collector will help there anyway.
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