281 clone project- taking orders now for last run of these..

dar303 · Joined: Jul 15, 2007 Posts: 97 Location: Sweden

Does anybody have two PCB's to sell?

Photon · Posted: Thu Feb 19, 2009 5:10 pm Post subject:

Finally busting a move on these. Rev.2 's no less.
Wiring commences tomorrow.

lexvortex · Joined: May 14, 2008 Posts: 155 Location: Toronto

Hey Photon, I love your panels Very Happy

Amazing stuff. I wish I had the know how to do those Confused

Cheers,
Dave

intellijel · Joined: Sep 10, 2006 Posts: 67 Location: Vancouver, BC

It says in the BOM to replace R7 and R8 with 1.2K/1.5K for 12V operation.

However the sentence can be interpreted two ways:

Do you mean R7 = 1.2K and R8 = 1.5K ?

OR

That R7 and R8 can BOTH be either 1.2K OR 1.5K?
(i.e. R7=1.2K R8 = 1.2K OR R7=1.5K R8=1.5K)

Which do you mean? (I assume the latter but I want to be sure)

toppobrillo · Posted: Sat Feb 21, 2009 4:00 pm Post subject:

hi yes that's right. just use either one-you could probably just change R9 to 6.2K, but 6.8K might be too big, and 6.2 isn't that common a value... i didn't test this. optimum range is probably around 1.35K for these, so it is up to you which value you choose.. 1.5Ks will give you a bit more control range.

josh

Sound · Joined: Jun 06, 2006 Posts: 842 Audio files: 1

Hello,

Finally I started the 281s Very Happy

I have seen topp, that you matched Q1 and Q2.

Is convenient to match also Q5 and Q6?

Thanks!

Sound · Joined: Jun 06, 2006 Posts: 842 Audio files: 1

Awesome your designs Photon. Really beatiful.

What is material front panel? How do you transfer the tone to the front panel? Ironing?

Photon · Posted: Sat Feb 28, 2009 6:47 am Post subject:

thanks.
The panels are etched brass. There is a thread here describing the process:
http://electro-music.com/forum/topic-26116-0.html

I'm still wiring the first pair...not much free time for my nerdular these days.

v-un-v · Posted: Sat Feb 28, 2009 10:43 am Post subject:

Hey Photon- gorgeous stuff indeed!

Thanks for the pix of the boards too Smile

I, (like many) get rather intimidated when choosing the right capacitors, and having these close up shots really helps Very Happy

fluxmonkey · Joined: Jun 24, 2005 Posts: 708 Location: cleve

zthee · Joined: Feb 20, 2008 Posts: 414 Location: Stockholm

Problem: I had D (from board A) connected to B instead of A (On board B) - so quadrature didn't work. Everything else worked OK.

So I changed the wiring, so it's correct. Now neither quadrature nor cycle will function.

I've checked end pulse out. And there is no output there.

My first thought is that there is something messing with IC3.3? or in that area?

- Think I found the error - Had a TL074 instead of a TL064. using a LF444 now, and operation have improved. Though not 100% yet.

One strange thing is that if i put it in cycle - and change the rate to faster it looses the end out pulse. Could be the LF444 though..

funkyfarm · Posted: Wed Mar 25, 2009 12:11 pm Post subject:

zthee · Joined: Feb 20, 2008 Posts: 414 Location: Stockholm

Oh, what I ment was that it stops cycling if i change the rate of any knob... I.e. if i change the rate while it cycles it looses the end out pulse and then stops cycling. But I think it's a problem with the LF444...? Not sure though. But until I've tried a TL064 I won't debug it any further.

numbertalk · Posted: Tue Mar 31, 2009 8:25 am Post subject:

Hi Topp,

Just starting to solder my board and I notice you provide pads for 2 configurations of trimmer - very convenient. But this made me wonder if this should be a multiturn - I always assumed it was a single turn but will a multi-turn be useful for this circuit?

Also, sorry if this was asked already, but I can't find D10 on the board or on the schematic - is this the diode to use for the pot for the external input to the Peak circuit?

Thanks!

numbertalk · Posted: Fri Apr 03, 2009 12:03 pm Post subject:

If anyone has any info about D10 as well as whether they used a single-turn or a multi-turn trimmer for their boards it would be greatly appreciated.

By the way here's the FPD file for a dual unit 2U MOTM-style panel I made. Really wanted to fit 4 boards behind 1 panel but it was just too much to squeeze in, so 4 boards behind 2 panels for me it is.

dual-buchla-281-2U-Rev4.fpd

Description:

Download (listen)

Filename:

dual-buchla-281-2U-Rev4.fpd

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3.14 KB

Downloaded:

271 Time(s)

toppobrillo · Posted: Fri Apr 03, 2009 9:13 pm Post subject:

hey don't worry about D10 i suppose it is the one you'd use for the external input, the trimmer just a single turn is just fine

@zthee, any luck?

zthee · Joined: Feb 20, 2008 Posts: 414 Location: Stockholm

Yeah! It all worked out in the end. It turned out to be something with the power supply.

It's very strange though - if I use my expensive bench PSU it refuses to cycle. Using my normal PSU (the one I use to drive the rest of the modular system) it functions perfectly! Very strange... They both leave ±15V and 1A.

drapdap · Posted: Sat Apr 04, 2009 5:31 am Post subject:

hello!

could anyone be so kind to pm me a picture of the soldierside of the board?
i ordered and paid for a pair, but they never showed up (and Topp isn't answering me). So i'd like to etch my own.

thank you!

robert

toppobrillo · Posted: Sat Apr 04, 2009 2:52 pm Post subject:

303monkey · Joined: Mar 11, 2008 Posts: 65 Location: NODNOL

Any news on the next run Josh?

zthee · Joined: Feb 20, 2008 Posts: 414 Location: Stockholm

I'd be in for another round!

drapdap · Posted: Sun Apr 05, 2009 3:32 am Post subject:

numbertalk · Posted: Sun Apr 05, 2009 6:06 am Post subject:

lanxe · Posted: Sat Apr 11, 2009 12:11 pm Post subject:

are these boards going to be available again? i would be in for four of them.

thanks,
Ryan