Voltage requirements for electric mistress

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6/5/2000 6:18 PM

Liam

Voltage requirements for electric mistress Hi All,     I've got an EH Mistress RI with a blown mains transformer. I've checked an original Electric Mistress and the transformer makes 22-0-22 V at the secondaries using my Fluke (not genuine RMS!) meter. Now I can only get 15-0-15 transformers which will fit into that size of box. Anyone know if this will work, or does the circuit actually need all those volts? plus and minus 30 V d.c as far as I can work out.     Thanks     Liam

 

6/6/2000 2:47 AM

Mark Hammer

Not looking at a schematic this second, so take these comments at the level you want, but here goes.     The EM *probably* wants +/-15v. A +/-22v transformer, after rectification, will provide MUCH more than that, so the EM will probably have some voltage regulation to bring that "too big" supply voltage down to size, and smooth it out.     Not sure what the circuit is, but the rule of thumb for standard 3-pin regulator chips (7809, 7812, 7815, etc) is that you should feed them at least 2 volts more than you want out of them. Following rectification, a 15/0/15 transformer more than meets this requirement. So, my educated guess is that, as long as it can supply the current needs of the EM, the *voltage* is perfectly adequate for the linear, CMOS, and BBD chips on board.     Do get a second opinion from someone with the schematic, though.

 

6/6/2000 7:15 AM
Sweetfinger	I just happen to have an extra EH Mistress transformer somewhere around here, 12 bucks if you want it. (includes shipping)

 

6/6/2000 8:10 AM
Liam	Unfortunately I live in the world of 230/240 volts, and I'll bet the one you've got is 110. Let me know if that's not the case - but thanks!     Liam

 

6/6/2000 12:31 PM

CJ Landry

I have one that came out of an EH Memory man that the owner got from Europe. He asked me to replace the transformer with a 110VAC xformer. The output is a 36VAC-CT transformer and the input is 240VAC. This is what the schematic for the EM requires. This should do the trick.     Also, I found a transformer that fits perfectly in the EH boxes but I cannot for the life of me remember where I bought it. I will have to do some digging and get the part number.     If you want the tranformer, e-mail me offline and we can work out a deal.     CJ Landry

 

6/6/2000 2:44 PM
paul perry	Those original EH '230v' transformers may have been shite, it's suprising how many blown ones I have seen here (Australia). Personally, I'd be happier making an external 'wart' kind of thing from a better built transformer.

 

6/7/2000 11:41 AM
Liam	Paul,     I certainly will not use a "genuine" EH 230 volt transformer, as they are most definitely shite, and blow at the slightest hint of a voltage surge. However I've found some similar transformers that are good quality, but lower voltage, which is what I want to try.     Liam

 

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