dual mn3005/8 expansion vero

pinkjimiphoton · January 17, 2013, 04:57:14 PM

hey guys, i got burnt on fleabay on a bogus mn3005. since it appears to do the same thing as the 3008 already in the project i was messing with, i went looking around to see what i could find, and found an excellent little circuit on steve daniel's smallbear site for running two mn3005's in series to effectively double the delay time. the schematic didn't look too hard, and with only 8 pins on each, i figured i'd give it a shot, so i worked up a vero. i've got room in the box (a standalone delay) to be able to fit it, so i figure i'll use some computer style ribbon cable from the vero to a spare 14 pin socket, and just make a plug in for it.

anyways, here's the schematic, not sure who to give credit to:

and here's my vero of it:

i've gone over it mondo times, and gotten it about as small as i dare to, tried to keep the cuts and jumpers to a min...having the bare spots in the middle of the chip made this A LOT easier!!!

i wanna build it up, but know myself... so if anyone wants to give this a once-over so i can go for it, a second or third set of eyes would be appreciated.
thanks.

may be something useful for someone else someday if it works as it's reported to.

gcme93 · January 17, 2013, 05:32:43 PM

Yepp I'd give that 100% after tracing every line's origin and destination.

Only thing wrong is that you've labelled C1 as Iuf rather than 1uf. I quite like the touch of roman numerals

pinkjimiphoton · January 17, 2013, 05:48:05 PM

oooooops.

close enough for rock and roll!!!!

thanks george, i guess i'll get on it tonite, and with a bit of luck, it'll work!!

pinkjimiphoton · January 18, 2013, 04:08:50 PM

wellp. i built the vero. tried it with the two chips i have. no dice. had to make a couple subs, used 1.96k and 465r resistors in series for the 2.4k's (that was the closest i could get with what i had on hand) and i made a non- polarized cap out of 2 2.2u caps with their anodes tied together in series for the 1k. caps in series divide like resistors in parallel, so the effective cap reads out at 1.2u.
close enough for rock n roll, i'd think.

voltages all are good on the daughterboard, reads the same as the original socket with the chip plugged in.

but it doesn't work. i get a little tiny bit of very quiet, severely distorted signal with the delay 100% wet. either or chip works fine, together, no dice.

so i'm thinking i may be wrong in my original thinking. i am reasonably sure the original chip is legitimately a 3008.

i WAS thinking the new chip was a re-branded 3008, but now i'm thinking it may be the same as the small bear 3005, where i found the schematic i made this daughterboard from. perhaps if i go and buy a pair from small bear, it will work.

advice would be appreciated. i'm gonna let the chinese vendor off the hook on this, because i assumed they were the same chip, but i don't think so now. maybe i'm wrong.

any ideas?

newperson · February 25, 2013, 10:49:19 PM

did you get this to work?

pinkjimiphoton · February 25, 2013, 11:53:22 PM

nope. not yet. i ordered some of the "fake" mn3005's from steve at small bear, but haven't had a chance to stick 'em in and bias it.
too busy with jobs and the occaisional fuzz.

newperson · February 26, 2013, 01:13:12 AM

I know that you made a vero, but I etched you a pcb from SB's layout. If you want it PM a mailing address and I will send it out to you. If you can/already have one etched and was just messing about with a vero layout feel free to say so.

Dave W · February 26, 2013, 07:48:25 AM

Quote from: pinkjimiphoton on February 25, 2013, 11:53:22 PM
and the occaisional fuzz.

Occasional???

pinkjimiphoton · February 26, 2013, 10:27:23 AM

well, i try to keep it down to 2-3 a week, dave... if i let the addiction take over, the world would get TOO fuzzy!!

pinkjimiphoton · February 26, 2013, 10:28:16 AM

Quote from: newperson on February 26, 2013, 01:13:12 AM
I know that you made a vero, but I etched you a pcb from SB's layout. If you want it PM a mailing address and I will send it out to you. If you can/already have one etched and was just messing about with a vero layout feel free to say so.

i'd love to try it. the vero appears to be good, but i can't seem to get the dang thing to work!!
pm sent, thanks newperson!

Marcvv · February 26, 2013, 10:55:16 AM

You may have tried it all but I do not read this in your posts so:
What delay circuit are you using this in?
If you put one of your mn chips in, are you able to get that delay working?
The biasing of an analog delay is pretty precise and biasing the double bdd needs the circuit to be biased for one bbd to start with in my experience. It is also easier with a scope.

Did you follow the directions on biasing an analog delay?

Marc

pinkjimiphoton · February 27, 2013, 10:27:46 PM

i don't know squat about biasing an analog delay.
i've tried putting in the first one, and biasing with the original trimmer, then adding the second and trying to find a bias point with the other. no dice yet.
but i haven't put much time into it, either.

Marcvv · February 28, 2013, 03:54:50 AM

If you want this to work you will need to put quite a bit of effort in it. Analog delays are not easy... Also if you want any help please give us the information asked.
What delay circuit are you working on?

About calibrating, biasing an analog delay you could look at the calibration section of the aquaboy:
http://www.madbeanpedals.com/projects/Aquaboy/docs/Aquaboy_ver2_revised.pdf

When I wrote if you tried putting in one BBD, I meant did you put the BBD in the original circuit without the expansion board. That way you can check if your BBD is actually working. Try this with both. Also note that you might have to calibrate it differently for each BBD to ind out if they are woking. This can be sometimes a very precise job. If after this it turne out that the BBD's are boh working, then I would calibrate the delay accoring to the instructions with one of them. Then You take it out and put that one on the expansion board, in first position, add the othe too and the calibrate the expansion board.

pinkjimiphoton · March 01, 2013, 02:58:34 PM

Quote from: Marcvv on February 28, 2013, 03:54:50 AM
If you want this to work you will need to put quite a bit of effort in it. Analog delays are not easy... Also if you want any help please give us the information asked.
What delay circuit are you working on?

About calibrating, biasing an analog delay you could look at the calibration section of the aquaboy:
http://www.madbeanpedals.com/projects/Aquaboy/docs/Aquaboy_ver2_revised.pdf

When I wrote if you tried putting in one BBD, I meant did you put the BBD in the original circuit without the expansion board. That way you can check if your BBD is actually working. Try this with both. Also note that you might have to calibrate it differently for each BBD to ind out if they are woking. This can be sometimes a very precise job. If after this it turne out that the BBD's are boh working, then I would calibrate the delay accoring to the instructions with one of them. Then You take it out and put that one on the expansion board, in first position, add the othe too and the calibrate the expansion board.

hi mark,
it's a vintage seiwa analog delay standalone unit.
it came with one mn3008 if memory serves... mark hammer suggested i could double the delay time with an mn3005. i had one, but it made no difference. so i ordered a pair from steve daniels at small bear, haven't even had a chance to mess with it, other things keep taking priority.
i've got the aquaboy pdf, but right now it's pretty much moot cuz i just plain don't have the time or inclination to play with it at the moment.
someone bumped this thread, asking if i'd gotten it working. the circuit works fine. i just haven't gotten around to messing with the replacement chips yet.

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dual mn3005/8 expansion vero