Rectos Q

[rzenc]

Hi,

I found some info regarding rectos that are contraditory against each other.. Can you help to clarify it?

On one magazine, author states that FWB can deliver 1.4x RMS AC (secondary) for Volts and 0.5x current. On another article, author suggests FWB delivers 1x RMS AC (secondary)..this got me puzzled..

For the sake of our sanity, can someone confirm this?
I have drawn a simple plan, however, I don't have any (24V * 1,4 = 33,6V) 35V e-cap on hands...gotta buy one to test it...just want to be sure before spending some coins..

Thanks in advance

Best Regards

R.

[PRR]

> FWB delivers 1x RMS AC

Wrong.

Cap-input: 1.414 * VAC(rms)
Choke-input: 0.9 * VAC(rms)

The current multiplier for cap-input "depends". 0.6 * IAC(rms) is often used. When not pinching pennies I like to buy AC current double the DC current needed.

> I don't have any 35V e-cap

Use 100V or 450V for a test.

If current is very low (just a voltmeter) you can use a quite small cap like 0.1uFd to check your math.

At lower voltages you must account for diode drop, 0.6V-1.1V per diode, or ~~2V for the FWB.

[rzenc]

Thanks PRR!!

I found on Merlin PS book (pg.31) different schems and example h. did the job (see attached image)

Thru a secondary 24VAC, I'm getting ~36VDC @ reservoir cap.


Use 100V or 450V for a test.

Although you suggest using it only as a test (to check math), I wonder why we are not supposed to employ e-caps below a minimum voltage? I can't remember where I read it..Any thoughts?

Many thanks!!!
Best Regards

R.

[sluckey]

You don't want to use caps at a higher voltage than they are rated for. BTW, everything I highlighted in this drawing is unnecessary in this low voltage circuit unless your caps are rated less than 36V. One single cap rated for 50vdc will do the job just fine.

[rzenc]

Thanks Steve!

I decided to left the series caps as is in order to have a lower voltage reference. I'm still owrking on this thing...

Best Regards

R.