Changes to make ST-35 work with 220 Volts ACSupply

[Shannon Parks]

I recently discovered this site and I am interested in building this amplifier.
I am currently in USA but would like to use this in India also where we use 220V supply.

I looked at the SCA-35 circuit and did some search on SCA-35 and found that it was a 110-240 model. Any one who has seen the Dynaco SCA-35 can they please confirm this.

What are the other transformers that can be used with this to make it work for 220 V.

All comments and directions are wlecome.

Vinay

Hi Vinay,

I know Dynaco made transformers for overseas sales of their amps, but don't think it was a dual voltage power transformer. Your best bet would probably be looking at Universal Hammond power transformers or something similar:
http://www.hammondmfg.com/300series.htm

I can't say I've used these yet, but I would probably recommend the 370HX at this time. This would grant you a measure of flexibility and ensure that you can listen to your diy amp <anywhere>. Good luck!

Shannon

[EWBrown]

The SCA-35s I've seen have the same transformer asn the ST-35 (PA-774), which is a 120 VAC input. Dynaco did make an overseas optional
transformer, with two primaries (and taps?), I'll look up and see if I have the number.

The Hammond 370 series have the dual primaries and taps, for any input
voltage combination from 100-240 VAC, 50-60 Hz. They do cost a bit more than the 270 series.

Since the input current of a 240VAC will be approximately half of a 120 VAC unit, will the ICL have to be changed to a different unit to have the same effect?

/ed B in NH

[Shannon Parks]

Since the input current of a 240VAC will be approximately half of a 120 VAC unit, will the ICL have to be changed to a different unit to have the same effect?

Ed,
Nothing slips by you. The IRCL, a Keystone CL-90 will technically be operating <just under> min spec, running around .4A (min for the CL-90 is .5A). I would SWAG that it is impossible to damage an IRCL with an under current situation (ie how could it dissipate more heat with less current? as heat determines the linearity of the resistance anyhow?).
I would assume that this part would be preferable to one of the small CL-series parts that can't handle much capacitance - especially at 240VAC. And yes, it will drop an extra volt, too. ::wink:

Shannon