Transistor matching for soundlab

[adambee7]

I'm just about to finish off my stripboard soundlab (x2) and i was wondering if anybody matched their tansistor pairs or purchased ssm2210ps. I would like to use the ssm but they are a b'stard to get hold of. Oakley sell them for £5.50 each but would it be better to build Rays transistor matching rig and match up 3904s that way. Oh yeah the 2k resistors r60-61, anyone go the temp comp route. Elby sell wire wound 3300ppm 2k resistors for $8 each. Just would like to hear what you guys used for this little synth. Cheers.

[jordroid]

I built Ray's transistor matching circuit on a bit of breadboard, it's a pretty simple to make and it seemed to work fine for me. I was surprised at how closely matched almost all of the transistors were within a batch, matching them almost seemed pointless. It's easy enough to do though so why not.

Mine tracks nicely over about four octaves, maybe a little less, but i bet i could squeeze a bit more out of it by spending some more time trimming.

I cheaped out and didn't install the tempco resistors and i do notice some drifting over time, i think it will be well worth it to install the tempcos and i plan to eventually, but it is quite usable without them.

Have fun, it's a great little synth!

[adambee7]

nice one. I'll give it a go as i have loads of 2n3904s from the same batch. cheers.

[adambee7]

In ray's schematic for his matching circuit did you use 200pf for the caps. Is 220pf ok for this circuit.??? Can't seem to get 200pf in the UK. Cheers.

[jordroid]

I don't remember what i did, but i would think that 220pf will be fine. It's a cheapy ceramic strapped across the 20k resistors, and it will probably be a 10% tolerance part anyways. If for some reason it is critical you could put two 100pf caps in parallel but i would just use what you have or can easily and cheaply get.

[adambee7]

cheers man

[adambee7]

Yeah that is a good circuit easy to build on stripboard. Matched up a load of them last week. Going to build the PNP one this week as i've got some filters to build. Well recomended

[LektroiD]

I'm interested in breadboarding a transistor matcher, anyone got the link to the schematic / build docs?

[adambee7]

Here it is. One for NPN and one for PNP.

http://www.musicfromouterspace.com/analogsynth/TRANSISTORMATCHER/TRANSISTORMATCHER.php

[fifteenrabbits]

I've decided to build the go-nogo version, however I don't understand the small portion of the diagram that shows the bypass caps.

There are three separate circuits marked "bypass caps"

I just don't know where to put each one.

Thank you so much,
Rabs

[fifteenrabbits]

So you know what I mean:

http://www.musicfromouterspace.com/analogsynth_new/TRANSISTORMATCHER/pdfs/transistor_matcher_go_nogo_schem.pdf

lower right hand side, and two in the upper center.

Thanks!

[fifteenrabbits]

just to clarify: I don't know where to connect the bypass caps.

If somebody could please take the time to tell me quickly, I'm in a rush as I'm building the synth with a high-school apprentice who only has two weeks left to finish his synth.

Thanks so much!

[mark_olson]

The bypass caps are drawn this way to keep the schematic from getting cluttered.

Put the ones at the top center where power enters the circuit.

The ones in the lower right go as close as possible to the IC power pins like C3 and C6 in this schematic:

http://electroschematics.com/wp-content/uploads/2008/10/subsonic-filter-circuit-schematic.gif

If I wasn't at work I could draw a picture or something but I am so I can't. Try googling "bypass capacitor" or "decoupling capacitor" and look at images; you ought to be able to see something that will bring it into focus for you.

Good luck,

Mark

[fifteenrabbits]

so the 22uF caps go where the power comes in?

[mark_olson]

[fifteenrabbits]

Thanks Mark!

I have a meeting with my apprentice later today and hope to have the matcher built by then!