Adding A supply to this B Battery Eliminator - Printable Version

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+--- Thread: Adding A supply to this B Battery Eliminator (/showthread.php?tid=17660)

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RE: Adding A supply to this B Battery Eliminator - NostalgiaRadioTime - 12-29-2017

Well I proudly tip my hat and offer a heartfelt thanks to Terry for his power supply schematic.  It works like a charm.  

The 10 volt winding can be dialed down to 1.5 easily with the potentiometer for the A supply. On the B supply, having only a 6k ohm adjustable resistor I decided to use two 5 watt ceramics I had in house instead. If you have a 10K ohm total adjustable resistor that would be ideal. 

I played around with the values (7k & 3K was too low) and found a 4k connected from the positive side of the 47 mfd electrolytic to B + and a 5k connected between the B+ and B - connections gave me 94 volts which was right on with what I was getting with ten 9 volt batteries strung together. Of course that was without a load. Once installed and the radio is playing, it drops down to 76 volts. I should have taken that into account and went with a higher value resistor between the B + & B - and a smaller value from the lytics to B + to have over 100 volts without a load. Then it would've been perfect. But, it plays great as it is, so I'm not complaining.

It took a lot of finagling to get everything to fit inside the enclosure box I got from Amazon: 

https://www.amazon.com/gp/product/B06XSQZ5M6/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

But I got it all in, plus added a toggle off/on switch and an indicator lamp.

Best of all, it fits nicely inside the cabinet!!

   

It's even flush with the back of the cabinet too:

   

Here is the bottom side of the box showing the toggle on/off switch, light and potentiometer to adjust the A voltage:

   

You need to use a 3 prong plug and connect the ground wire from the radio chassis to the ground wire in the cord to eliminate buzz (unfortunately I only had a white colored cord on hand but that's a minor detail).

I'm very pleased with with this power supply and would recommend it to anyone who wants to convert a 90 volt "B" / 1.5 volt "A" battery powered farm radio to run on AC.

Thanks again, Terry!

   

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RE: Adding A supply to this B Battery Eliminator - NostalgiaRadioTime - 12-29-2017

I should also mention the speaker in the radio is a smaller diameter replacement 4 ohm permanent magnet speaker I had on hand. The original was blown... the cone was bowed outward and it had no volume. Because the replacement speaker is not quite as tall as the original, the box fit nicely in front of it in the cabinet. With the original speaker you may have to leave the cover off of the power supply box to get it to fit in the cabinet (if you use the power supply in a 39-70 cabinet). Of course, if you leave the box outside the cabinet, it's not an issue... plus you'd have the option of using it for other battery powered radios as well.

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RE: Adding A supply to this B Battery Eliminator - Stall-U-Rated - 12-29-2017

SWEET!!   Whats the front look like?  What about the original speaker? would an original size fit if you found one?

Steve

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RE: Adding A supply to this B Battery Eliminator - NostalgiaRadioTime - 12-29-2017

Thanks...the front is pictured in the December Phinds thread. Yes an original speaker would fit. I had this one here, and it fit and sounded good so now it's no longer taking up space hanging on the wall

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RE: Adding A supply to this B Battery Eliminator - Radioroslyn - 12-29-2017

Good job!!! I'm impressed!!
Glad to help out.

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