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Rudi_Ratlos 22nd April 2011 10:47 AM

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Some time ago my friend Joe asked me, if I would like and design an AMP with 2 pairs of TO-3 output transistors.

Both, Joe and I, have a couple of MJ2119x transistors at hand, which are worth to be used.

I studied some of the DIY - AMPs in this forum and felt, that Michael Bittner's SYMASYM would be the best match to do the job.

I transferred his SYMASYM version 5.3 into EAGLE, did not change anything in the frontend, but added the pairs of TO-3 in the backend.
DADOD (thank you very much!) simulated the resulting AMP in LTSpice: the results look perfect!

I have attached the schematics as a PDF-file.

After finishing the layout, I had some space left on the bottom right and left side of the PCB and implemented a standard capacitor-multiplier
for the frontend there.

This is the resulting layout:

The red lines indicate tracks, that are running on the top side.
The TO-3s will be mounted on ALU-brackets.
The size of the PCB is 150 x 100mm.

Joe and I want the PCBs to be etched professionally, having the same quality as the PCBs, that I offered in my group-buys
for Carlos Mergulhao's DX Blame (see the picture below).

Since the SYMASYM, the backend and the capacitor-multipliers are proven circuits, we won't do prototyping.

In order to get a decent (about 13€ per PCB) price from the etching company, I must order at least 10 PCBs.

Maybe some of you like this design (SYMASYM with TO-3) and join the party.
I am sure, it will give you a big bang for your bucks.
Take a careful look at the schematics then and tell me, if I shall change anything.

Best regards - Rudi_Ratlos

pinkmouse 22nd April 2011 10:52 AM

Nice project! However, the combination of rounded and angled traces does jar a little. ;)

Rudi_Ratlos 22nd April 2011 10:57 AM

I will do some final cosmetics to the layout, be sure!

Best regards - Rudi_Ratlos

pinkmouse 22nd April 2011 11:01 AM

Yeah, I know. I frequently spend longer tidying up cosmetic stuff than working out the actual layout. :)

metal 22nd April 2011 04:29 PM

3 Attachment(s)
Thanks to Rudi who created the asc file and sent the other models included in his asc file.

Neutrality 1st May 2011 10:53 AM

Nice layout.

Rudi_Ratlos 11th May 2011 10:19 AM

I have just finished the "cosmetic improvements" of the layout and the silkscreen of the TO-3 SYMASYM - PCB.
Here it is:

Since there is some interest in the PCB in the German Analog-Forum, I will be able to order the minimum amount of PCBs.

Rich: are you still interested?

Best regards - Rudi_Ratlos

jmmartins 13th May 2011 08:25 AM


I'm also in for a couple of PCB's


digits 13th May 2011 08:45 AM

Rudi, I see you moved the traces there around the top left TO-3, I didn't like the first one, and the second one you got almost right. I see you now allowed space for the mounting screw, but if possible I suggest you bring the left trace back out to the side to reduce capacitance between the two traces, unless of coarse you think a little in that position is benneficial, other wise nice work. I know Carlos would drive you mad to get all those TO92 transistors in a row

Luke352 13th May 2011 10:36 AM

Do you have an idea on what postage would cost for a pair of boards to Australia? I may be interested in a pair.

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