[sdiy] another year, another day, another transformer request

[Mike Bryant]

Well what I would do, and I bet a some people will object, will be to get rid of D1 and C3, then replace IC1 with a pin-compatible switching 7805 so that it doesn't get red hot,
https://uk.rs-online.com/web/p/switching-regulators/1934015

Then tie the input of the switching 7805 to the 7815 in at C5.

Then depending on the current requirement of the Beatric interface, wire either a linear or switching 9V regulator also to the 7815 at C5.
https://uk.rs-online.com/web/p/switching-regulators/1933977

________________________________
From: Todd Sines <sines_list at scale.la>
Sent: 06 February 2024 21:25
To: Mike Bryant <mbryant at futurehorizons.com>
Cc: analogue heaven <analogue at hyperreal.org>; synth-diy at synth-diy.org <synth-diy at synth-diy.org>
Subject: Re: [sdiy] another year, another day, another transformer request

Maybe I should back up and list my full needs:

I want to power both the CMU800R and 5-10x System 100M modules.. *AND* the Beatnic.jp interface (9V) from one supply.

E-Licktronic tackled the M-191 Supply  here
http://www.e-licktronic.com/home/4-m-191-x.html

And recommended this toroidal transformer at Mouser
TRIAD VPT30-1670

This densely layered schematic shows at the bottom left the +/-15V and +5V from the transformer; the toroidal above could drive the +/-15V from the taps, then use the 7805 to get my +5 for the CPU portion of the CMU.
https://www.synthxl.com/wp-content/uploads/2020/01/Roland-CMU-800-Compu-Music-Schematic.pdf

Am I missing something?


Todd

On Feb 6, 2024, at 2:51 PM, Mike Bryant <mbryant at futurehorizons.com> wrote:

First thought is do the 17V and 9V need to be isolated from each other ?   You might be able to use a 9-0-9V transformer to get the 17V (as 18V) and a large capacitor(s) to level shift the 0V line and one of the 9Vs to create 9v.
________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Todd Sines via Synth-diy <synth-diy at synth-diy.org>
Sent: 06 February 2024 19:27
To: AH <analogue at hyperreal.org>; synth-diy at synth-diy.org <synth-diy at synth-diy.org>
Subject: [sdiy] another year, another day, another transformer request

It's official, my 117/120V transformer has sh!t the bed in my 120V CMU-800R.

Last post was from last year, also on SDIY
https://synth-diy.org/pipermail/synth-diy/2023-February/131184.html

No doubt, I *would* like to buy a few toroidal transformers from Florian, but then I'll want the VCM, module and the SQ-3P module, and it will rise up to several hundred € before I'm done.

In the meantime, I'm looking for a dual tap transformer -- AC120V in, 17V and 9V out. I don't see any of these on Syntaur, Sam.

Leaning towards this Hammond toroidal transformer:
https://www.hammfg.com/electronics/transformers/power/1182

Specifically,
https://www.hammfg.com/part/1182Q9

Are there by chance some cheaper, faster, or even Amazon equivalents?

PS. The reason for the CMU:  With a Beatnic.jp CMU800-MIDI converter, it can also function as a MIDI/DIN Sync converter, plus 8-channel MIDI-CV converter, a pile of chip-tune style square wave oscs, a low-rent 606 drum module, and I've tapped the supplies to drive my System 100M off it to boot. And I have two -- 1 220V, 1 120V.

Todd

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