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TR-808 Voice STRIP Boards...
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-minus-



Joined: Oct 26, 2008
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PostPosted: Thu Sep 20, 2012 2:06 am    Post subject: Reply with quote  Mark this post and the followings unread

-minus- wrote:
Check that your components are in the right holes.


ROFL

I have updated the diagram on page one now. It should be correct. With that jumper as it was, there would be no pull up resistors (R21 and R22) from the transistor bases of T1 and T2 to the +V. They were being pulled to GROUND! Embarassed
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elmegil



Joined: Mar 20, 2012
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PostPosted: Fri Sep 21, 2012 10:46 am    Post subject: Reply with quote  Mark this post and the followings unread

I am sitting waiting for service people to respond, so here I am Smile

I believe I have found the solution for the click on the bass drum. I have yet to test it, but I wanted to let you know, minus, because you were redoing the stripboard layout...

The click section of the circuit is, if you reference Eric Archer's schematic, the lower section with the parallel cap and resistor, then resistor and diode to ground, going into the positive input of IC1A.

If you put a 1K or 2K trimmer between the two parallel pieces and the 4.7k resistor (instead of a wire) wired as a variable resistor, you can adjust the click response. I have tested by grounding that point, and found that the click pretty much went away. I simulated the circuit and it looks like a 2k there reduces the current spike there enough to be negligible, while leaving a reasonable range of adjustment. I only have a 1k trimmer though, so I'm going to try that later.

I was thinking though that if you could arrange the stripboard so that you could optionally put a trimmer there or a wire, you could let the builder choose between "original" layout and being able to adjust the click. In fact, if I were to wire it to a panel pot I could make it directly adjustable as well... though I'm not sure you can get panel pots down to 1k / 2k, a 5K would probably work as well, just not have as much useful adjustment range.
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-minus-



Joined: Oct 26, 2008
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PostPosted: Fri Sep 21, 2012 2:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey thanks! I've just woken up... I'll read through what you have said a few times and respond shortly. I did redo the layout. Laughing I'll do some tests myself. I'm about to leave town for 10 days so if I don't have time in the next few hours, it will have to wait until I get back.
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roglok



Joined: Aug 28, 2010
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PostPosted: Fri Sep 21, 2012 2:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

Posted this over at Muff's today -
I found that the click sound changes considerably depending on the trigger input conditioning circuit. Try using a 33nF or 47nF instead of the 100nF after the rectifying diode. I haven't actually measured the resulting trigger width, but to my ears the click sounds a lot better and less prominent...
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elmegil



Joined: Mar 20, 2012
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PostPosted: Fri Sep 21, 2012 2:58 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'm triggering with the original method (1ms pulse from a CPU in my case an Arduino) so the conditioning doesn't help me any, but that's a good find for people who aren't as insane as I am Smile


BTW I found that 1K/2K really made very little difference in the actual circuit. A 10K pot does a reasonable job, but seems to affect overall tone some too.
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roglok



Joined: Aug 28, 2010
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PostPosted: Fri Sep 21, 2012 3:38 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
I'm triggering with the original method (1ms pulse from a CPU in my case an Arduino)


Oh, right! Very Happy

Are you trying to get rid of the click altogether? Afaik it's a feature of the 808 bass drum. My concern was that the click didn't sound right with a too wide trigger pulse, as in 1nF = floppy and 33nF = tight.
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elmegil



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PostPosted: Fri Sep 21, 2012 3:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

Definitely don't want it gone, there needs to be some impact tone. But my build at least it seems a lot louder than it ought to. Since I've never had an 808 to actually hear what the original sounds like it may just be me Smile
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-minus-



Joined: Oct 26, 2008
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PostPosted: Fri Sep 21, 2012 3:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

You guys are working hard!

I think the click does appear to be too loud, to me anyway. Without the click it will lose its punch. However, it would be nice to knock it down a little, or have a pot to control the click if you wanted that feature. I used to like a huge decaying boom, but of late I'm preferring a short solid thump. A sign of getting old perhaps?

I think we can agree the click is an issue we are all coming up against. If we can work out a solution, I'll draw up the stripboard diagrams and post here. I should have a go at the other voices soon. I like that retro hand clap!
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elmegil



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PostPosted: Fri Sep 21, 2012 6:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

Try putting a 10K or 15K pot there on yours, minus and see what you think. I'm pretty happy with the 10k overall, though it's a balancing act between that and tone to not lose the 'crisp' attack.

Here's the mod as proposed. (forgiveness for the awkward placement, basically built it out of cut & paste of other parts of the original image)


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elmegil



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PostPosted: Sat Sep 22, 2012 9:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Rawr, my stripboards are all 19 x 34, not 25 x 39, so most of the rest of the layouts are not feasible at the moment....
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elmegil



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PostPosted: Sun Sep 30, 2012 6:20 pm    Post subject: Reply with quote  Mark this post and the followings unread

Planning diagram done for doing the snare on protoboard, hopefully will have a snare sometime this week....
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elmegil



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PostPosted: Mon Oct 15, 2012 10:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

Finally got the snare "working"--my trigger circuitry had two stupid mistakes.

Here's the sample, kick and snare together with the fixes in place:

http://electro-music.com/forum/phpbb-files/kick_and_snare_652.mp3

What's weird is that the snare accent and trigger inputs have to be reversed for the snare to behave as I expect. I'm also getting a more crackly white noise sound than I think I should, but that could simply be my choice of noise transistor.

I have larger stripboards now, so I will be proceeding with the cymbals and such from this thread sometime soon.
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-minus-



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PostPosted: Mon Oct 15, 2012 11:28 pm    Post subject: Reply with quote  Mark this post and the followings unread

That sounds pretty good to me. I should un-bag my snare board and compare. I'm in the middle of trying to get my old Lunetta boards behind panels and in a case. Once that is done I have a load of other stripboards to put in a second case.... then there are all these drum modules to deal with. PLUS a sequencer to make! Good to see you are making progress. I have been reading your posts. That PN 100 transistor I used for the noise is simply a replacement for the original 808 one. I forget offhand what Roland or Eric Archer used. I got mine from Jaycar:

http://www.jaycar.com.au/productView.asp?ID=ZT2283

There is a PN200 too which is the PNP.

Your sound clip seemed to cut out after 7 seconds but it was enough to get the general idea.
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mrmrshoes



Joined: Feb 19, 2011
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PostPosted: Tue Oct 16, 2012 3:09 am    Post subject: Reply with quote  Mark this post and the followings unread

nice work man.

the snare sounds great.
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elmegil



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PostPosted: Tue Oct 16, 2012 5:13 am    Post subject: Reply with quote  Mark this post and the followings unread

Cool, thanks Smile

Yeah, I only meant to do 2 bars, but garage band apparently pays attention to other tracks length even if they're all muted, and made the MP3 the length of the longest track recorded.
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elmegil



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PostPosted: Tue Oct 16, 2012 8:13 pm    Post subject: Reply with quote  Mark this post and the followings unread

Playing around with a more complex sequence coming out of the Arduino, I found that it sounded interesting if I jumped the input level of the bass drum alternately to over drive it...

Might be an artifact of the battery based 4 input mixer too, but I like it.


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-minus-



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PostPosted: Thu Oct 18, 2012 6:16 am    Post subject: Reply with quote  Mark this post and the followings unread

Well done! And with pictures too. Good to see! Our man in Chicago never sleeps. Laughing You must be ripping through the caffeine. You're going to have some great percussive sounds to your synth. Those drums sound really organic to me. I wouldn't worry about the snare- it sounds pretty good. We can get so tied up with these circuits. In the realm of the bigger picture, I don't think many people would notice what niggles us for days or weeks. Keep up the good work!
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elmegil



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PostPosted: Fri Mar 22, 2013 7:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

Back to this again....building the original strips that minus posted, and I find that I have no 18nF caps! I have 15's....

I get the idea that if I use a 15nF for one of the two cowbell oscillators I should maybe go back up to 100k instead of 68k for the resistor in series with the trimmer. I think I'd be ok guessing at that and going with it, since there's a trimmer there too.

BUT

If I use 15nF for the other two 18nF oscillators, is that likely to be a problem? All the rest of these are just "making noise" right?

Anyone have any thoughts on that?
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-minus-



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PostPosted: Fri Mar 22, 2013 8:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

I found that the tuning of the two oscillators sounded better to my ears when tuned higher (I think) than the frequency specified. As for the other oscillators, they are contributing to the mix of what makes the noise or sound source. How important their frequency is, is anyones guess as only the frequency of the tuneable two are specified on the original schematics.

You could either go with a close value for the capacitors, or find some circuit emulator online to find the frequency with the specified components then substitute the caps and adjust the resistors to get the specified frequency.

Or I could get my board out and do some measurements with a scope. This last option may take a little while. My scope usage is rare and when I do need to use it, it takes several Youtube videos to jog my memory as to how to operate it. Laughing My boards are awaiting an enclosure still, but it's on its way. I have a huge backlog of completed boards but I have been building panels this year and enclosures... I can dig out the boards and measure each oscillator if need be.
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elmegil



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PostPosted: Fri Mar 22, 2013 9:18 pm    Post subject: Reply with quote  Mark this post and the followings unread

I think I'll just give it a shot and if it doesn't work out, I can always throw some 2nF caps across them on top of the board. I think 17 is likely to be plenty close enough to 18 Smile
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elmegil



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PostPosted: Sat Mar 30, 2013 9:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

Found a minor error in 3 of 4, hi hats....

R19 is labelled "C19". I'm 99% positive it's R19 Smile


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-minus-



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PostPosted: Sun Mar 31, 2013 10:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Embarassed Thanks for letting me know. I have fixed that on the original and uploaded it.
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elmegil



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PostPosted: Sun Mar 31, 2013 8:41 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hurm.

I have some medium-large stripboards (4" x 5") that I'm using and I've mapped out how to put all 4 circuits onto 2 stripboards. This first one is the sound source + the hi hats, next I'll put my attention on the cymbal and cowbell....

I have the closed hi hat working fine, but the open hat is not getting any envelope, it's just constant noise. I did have some shorts earlier that were causing R1 to burn, but those are resolved....I will have to see if perhaps I've messed up some transistors.... Need more study of the original schematic, apparently Smile
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PostPosted: Mon Apr 01, 2013 1:22 am    Post subject: Reply with quote  Mark this post and the followings unread

OK good. At least you have the closed part working. I'm fairly certain the layout is correct, although of course mistakes can happen. I can always double check with my working stripboard if you get stuck.
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elmegil



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PostPosted: Mon Apr 01, 2013 4:47 am    Post subject: Reply with quote  Mark this post and the followings unread

What I found before going to bed ridiculously late was that even with T3, T6, T7, and T8 removed, I have nearly 15V at the emitter of T3. This should not be; removing those guys removes all the active paths that get me to 15V, so there is not a bad transistor. And I just checked and there is a dead short to the 15V rail, so....just gotta find it.

Edit: And 5 minutes later it's trivial: insufficient cut between this section and the +15 that went to the collector of T8. We have hi hats Smile
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