Adding A supply to this B Battery Eliminator - Printable Version
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Adding A supply to this B Battery Eliminator (/showthread.php?tid=17660)
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Adding A supply to this B Battery Eliminator (/showthread.php?tid=17660)
RE: Adding A supply to this B Battery Eliminator - David - 12-17-2017
Back on April 1 2016 I posted a picture of a power supply I was using on a M Wards farm radio. Sorry but I do not know how to repost that info from the old post. Contained a isolation transformer and a A,B,C power supply. Simple to make. David
RE: Adding A supply to this B Battery Eliminator - klondike98 - 12-17-2017
Here ya go David. The link to your post is: http://philcoradio.com/phorum/showthread.php?tid=14126&pid=105702#pid105702
RE: Adding A supply to this B Battery Eliminator - David - 12-17-2017
Thank You. David
RE: Adding A supply to this B Battery Eliminator - Arran - 12-18-2017
If you want to isolate the B+ supply from the power line you could look around for an old style razor outlet transformer, and use one of those alongside a low voltage transformer for the A+ supply, make sure you find one that can deliver at least 500 ma or more as farm battery sets typically have the tube filaments connected in parallel . Another method some people use is to use several small transformers and connect the secondaries back to back to get the B+ side, I don't really like this method as it gets bulky and complicates what should be a straight forward power supply.
Regards
Arran
RE: Adding A supply to this B Battery Eliminator - John Bartley - 12-18-2017
One simple way to get the isolation, a chassis, and some of the chassis parts you need is to find an old Blonder-Tongue (or similar) UHF Converter. I hope it's not sacrilege to suggest this....
Many of the UHF converters have two miniature tubes, so there's your tube sockets, already set into a chassis. Many of them also have a power transformer with a 120vac primary and 6.3vac and 120vac secondaries. There's your power sources for the "A" and "B" voltages. The converter has a bakelite cabinet that already looks vintage, so all you have to do is wire it up and set it near the battery radio, then hook it up. You don't really even have to hide it. If you use LM317 style regulators for the voltages (the appropriate ones of course), then you can use the controls holes in the cabinet and chassis for voltage control pots, and even that will look authentic to the unsuspecting viewer.
just a thought....
RE: Adding A supply to this B Battery Eliminator - NostalgiaRadioTime - 12-22-2017
Thanks for all of the suggestions. I have all of the components needed now for the schematic Terry drew up and will attempt to build that in the not to distant future. As for now, I'm still trying to get the radio itself to function as it should, temporarily using ten 9V batteries for the B and a 1.5V flashlight battery for the A. The batteries power the radio fine for testing, but long term because of the load for the filament circuit I can see how it will go through a lot of flashlight batteries. May start another thread on the chassis restoration of the radio itself if it continues to misbehave. Already found the primary of the OSC coil was open.
Quick question for Terry....on the LM317T, is there a designated IN and OUT pin, or can either of the two outer pins be used as in?
RE: Adding A supply to this B Battery Eliminator - Radioroslyn - 12-23-2017
No each pin has a specific purpose.
RE: Adding A supply to this B Battery Eliminator - NostalgiaRadioTime - 12-23-2017
Thanks, Terry. Bet you can guess my next question....how do you know which is in and which is out? Is there some kind of a mark the indicates which is which (that I could see under a magnifying glass because the dern thing is so tiny)?
RE: Adding A supply to this B Battery Eliminator - David - 12-23-2017
[attachment=15074]
Hope this link works https://www.onsemi.com/pub/Collateral/LM317-D.PDF Will try and as a attachment. When I use L317 if it will be converting more than one watt to heat I install a heat sink if it is nothing more than a small piece of alum.
RE: Adding A supply to this B Battery Eliminator - Radioroslyn - 12-23-2017
One important point is that the output pin and the metal mounting tab are internally connected together. This means that unless you use an insulator between the tab and heat sink the heat sink will have the output voltage on it. There are kits that contain a flanged washer and a thin piece of mica to insulate the devise from chassis ground.
https://www.google.com/search?q=mounting+to220+heatsink&client=firefox-b-1&source=lnms&tbm=isch&sa=X&ved=0ahUKEwidvLT9xKDYAhWChOAKHU8xBAUQ_AUICygC&biw=1280&bih=661#imgrc=Zpedz7-KGKBdcM:
I have some junk ss stuff around to scavenge bits from. Old computer p/s are a good source for plastic covered wire, lv ecaps, bridge rectifiers, single diodes, heat sinks, and mounting parts for to-220 semiconductors. Most of the time with the semiconductors you'll find on the p/s board you can google the p/# to find the specs. I've found a number of 800v 3A bridge rectifiers which are handy for building hv p/s. You wouldn't think that a 24v p/s would have such hv parts.
RE: Adding A supply to this B Battery Eliminator - David - 12-23-2017
[attachment=15079]Hope it works this time
RE: Adding A supply to this B Battery Eliminator - David - 12-23-2017
RE: Adding A supply to this B Battery Eliminator - Stall-U-Rated - 12-23-2017
Heres my mot wards radio.. It uses the same A and B voltages. Works great with the mess of batteries as you described.
My g/f bought it for $3 and gave it to me.. Sadly, i had to replace EVERY tube in it because someone blasted ALL the filaments with the wrong voltage trying to power it.. (All original WARDS tubes were present)
Its fun to take it out from time to time and power it up..
Steve
RE: Adding A supply to this B Battery Eliminator - NostalgiaRadioTime - 12-23-2017
Thanks for your help, Terry & David. It makes a bit more sense now.
RE: Adding A supply to this B Battery Eliminator - Radioroslyn - 12-23-2017
If you want to replace your dial cover give http://67.20.74.185/jmpalm/Inventory.htm a try. He doesn't list your 93BK401 but may have one that will fit.