Noob question re wiring 6.3-0-6.3 secondaries for nominal 12.6V output

  • Thread starter Thread starter Deke609
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Deke609

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All - Just want to double check my thinking here.

In the hopes of bumping up my supply voltage to the BeePre filament heater circuit I am playing around with dedicated filament heater transformers - specifically the Hammond 166L12B - which is spec'd as 25VA and 12.6V (C.T.).  I plan to try one 166L12B for each filament.

Am I right that I should just cap the center tap (leave it disconnected) and wire the remaining two secondary wires into a 4-diode bridge?

Or is another method of wiring recommended - e.g., one that makes use of the center-tap?

many thanks, Derek
 
Thanks PB. Yes, mains power is now 115V but I will be bumping it to 120V +/- 1.5V with the autoformer and buck/boost setup (which I have yet to build - will use the variac in the interim to test).

cheers and thanks, Derek
 
Well, that transformer is for 115V.  I don't recommend giving Hammond transformers more than they say they'll handle.
 
OK. I may have to check with Hammond about this - I think they only make 115V and 117V variants - which seems odd for North America where wall voltage can be as much as 125V or more.

I figured than since I'll be drawing a max of 1.35A and the trafo is rated for 2A I'd be ok and not overtax the primary winding. But maybe my thinking about this is wrong?

thanks, Derek
 
Thanks for that, PB. I am going to email Hammond and if they say anything over is 115V is a no go, I will get the Edcors.

Is this is an issue of the dielectric strength of the primary magnet wire coating?

cheers and thanks, Derek
 
Many thanks PB. I was prepared to deal with over voltage output, but hadn't considered saturation. I put in an inquiry with Hammond.
 
Hammond reports that 120V mains with 1.35A draw from the secondaries is no problem for the transformer.  It just bumps up raw output from 12.6V to 13.2V - something I've already addressed with a 15W dropping resistor. So all good!

cheers, Derek
 
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