minimoog clone and equivalent parts.

[did_poutrator]

Hello everybody,

I am making a minimoog clone, this is not yet finished but it is on his way. I have already make the alimentation board , the rectifier board and the keyboard board which I have seperated from the contour generator board.

I would like to do the last VCO version.
I have managed to find some of the hard to find parts but I still have problems with the ua726. These are very expensive and I have read on this forum that the ones on ebay were not working or were false 726.

Here is the point. What can I do to replace those 726. The only information I have find on the net or by contacting diyers were that I could replace the 726 by a LM394 and change the values of the 2 resistors connected to pin 1 on the schematics. R63 become 23.2K instead of 2.32 and R64 become 1K/3000ppm tempco resistor instead of 100Ohms.

So , do you have more informations about it? Or another way to replace the 726.

Thanks to all.

[synthnerd]

Hi there,
I joined this forum just to reply to your mail.
Don't try the clone the Mark 3 VCO board.
Apart from the uA726's there were a lot of hybrid resistor arrays on this board. It had a huge amount of circuitry on it and even if you could get 726's at great expense, the hybrid resistor networks were custom parts and quite impossible to get. The Mark 2 board was used by 10,000 of the 13,000 Minimoogs produced, and contains nothing impossible to get, and it's performance is quite adequate (this is a Minimoog after all).
Years ago I designed (but never built) a clone with improvements to the Mark 2 circuitry, with Sync between Oscs 1 and 2 and using 3 x 3046's with the Tempco resistors strapped across them.
One day I'll get to build it.
All the best...

[blue hell]

[did_poutrator]

On the minimoog schematics , the values of the network resistors are given, I wanted to make a custom network with real resistors at 1%.
As I don't have made the printed circuit board yet , It should work, I hope so.

But, I am interested in the 3046 VCO board. I have chosen the 726 one because it was easier to find the PCB already drawn. I am a little bit scared to make the pcb myself from the schematic, the few times I have done that, there were some small errors.

As I am about to spend 10 years making this clone, so I am ready to try the 2 VCO types. I would be really glad if you send to me or in this forum , the mark 2 pcb you drawn.

[tomcat]

You can get the 726 on ebay from a little bit shady dealer in asia. They are clones and no NOS! But friends told me they work. I have some here, but didnt use them till now.

[did_poutrator]

thanks for the advice , but I think this is a little bit expensive for obsolete transistors. Otherwise (?) , the mod for LM394 allow me to change for 726 if I want.
bye