tips for making 208 Instrument definition cards?

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misa
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tips for making 208 Instrument definition cards?

Post by misa » Fri Mar 13, 2020 6:10 pm

Is anyone making their own cards for the Easel? as in "I solder resistors into cards and hope everything will sound recognizably like this patch I spent hours preparing"?

any tips?

Like: to get to a value of 3, it says in the manual, you need 390K of resistance. How close do I have to get to 390K (I am asking about the pulse trigger switches, not the values for any sliders). I don't have any 90K (or 390K), but 300K+100K or something off like that. Would that work?

Also I have some resistors that are way off the labelled value -- How much (percentage) is allowed here?

thanks for any tips!
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Re: tips for making 208 Instrument definition cards?

Post by papz » Sat Mar 14, 2020 12:13 am

400k (300k + 100k in series) should work but why not rather get a set of 1% resistors of various values you may need ?
They cost $0.012/ea only.
https://www.taydaelectronics.com/resist ... oup-2.html
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I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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Re: tips for making 208 Instrument definition cards?

Post by misa » Sat Mar 14, 2020 8:30 am

Thanks papz, very good point!

I was trying to get a bunch but must have done something wrong bc only half of what I thought I ordered was actually on the invoice and inside the package.

So I was trying to improvise last night...;)
OUT NOW: GRAT - CHAOSMAGIC. on CD (digifile) and download, three dark ambient tracks rooted in Magic Realism. CHECK IT OUT HERE

Buy it now: "Heart Murmur" 10" vinyl on Bandcamp (solo Buchla 200e, no overdubs, recorded live in Berlin) out now everywhere!

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Re: tips for making 208 Instrument definition cards?

Post by KSS » Sat Mar 14, 2020 8:40 am

Take one card and solder individual sockets taken from a machined pin strip or IC socket into the various positions of the card you're planning to use. Eventually you might end up with a whole 'proto' card full of these sockets, which you've broken out from their common plastic bonding to one another.

Now you have a pluggable 'proto' card. You can put the resistors you have into the sockets -in series or parallel just twist their ends together- and test the result. You can also put a pot in place by wire wrapping or soldering two solid copper pigtails to it. Adjust the pot to taste, then measure what its actual resistance is. Repeat using individual resistor(s) to arrive at the value you measured. Don't forget that you can use both parallel and more than two in series resistor chains. Two 47K and your 300K bring you closer to the desired 390, at 394K.

With the socket enabled card you've taken a must get it right, to an iterative process. Whatever you learn and like on the plug-in proto card is then transfered to a fresh card, where you can expect the results you've already proven.

The variations you're seeing from measuring the resistors you have are normal. As for how far off they 'should' be, the tolerance band on the resistor is the answer. A 1% 100K resistor can be anything from 99 to 101K, and still be within tolerance. If you have older carbon comp resistors, they can still be used even though they may have drifted in value over the years. They might be 10% so even a 90 or 110K reading for them is within tolerance, and they might by now be even farther off. Don't worry about it.

Just use the actual measurements you get in your calculations and decisions about which resistors to use.

Depending upon how stable you want your results to be, you might want to consider getting a bunch of 1% 100 or 50PPM resistors from a reliable source like Digi-Key or Mouser. Those Tayda R's will work, but many have thin brittle leads and may not actually have the temperature drift rating claimed. YMMV.

Over time you might find that some of the most often used sockets on your pluggable proto card have become less reliable. Simply replace the worn out machined pin socket with a new one and carry on.

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Re: tips for making 208 Instrument definition cards?

Post by papz » Sat Mar 14, 2020 5:00 pm

Tayda's "Royal Ohm" resistors have thick leads and are good quality.
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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Re: tips for making 208 Instrument definition cards?

Post by misa » Mon Mar 16, 2020 3:33 pm

Thanks KSS and papz for even more supergood tips.

Isn’t it ironic that in a lockdown that’s getting more and more all encompassing it’s still possible to order electronics parts from (of all places in this crisis) CHINA! ;)

I hope you all are doing well. I take social distancing seriously and try to go around as though I already have the virus and to not spread it to others. (I have no symptoms, but Cologne is a hot spot)
OUT NOW: GRAT - CHAOSMAGIC. on CD (digifile) and download, three dark ambient tracks rooted in Magic Realism. CHECK IT OUT HERE

Buy it now: "Heart Murmur" 10" vinyl on Bandcamp (solo Buchla 200e, no overdubs, recorded live in Berlin) out now everywhere!

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