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Hi All:
I am in the process of restoring an old farm radio that ran on an A and B battery. So I am designing an eliminator for it that will be solid state, efficient and will have a few other neat features. I have the basic idea and configuration figured out and will start the build in a few weeks.
In total there will be four power supply topologies required to fit into the box – a true smorgasbord of technology that will be easy to build and maintain.
Would anyone else be interested in something like this? Send me an e-mail if you would like more information.
Regards,
Not to be picky Gerry, but a farm radio is one that runs on a single dc voltage. Sometimes seen with set of alligator clips that would clip to your tractor or car battery (6 volts of the day) or 32 volt battery pack that would be charged by windmill or stationary engine with charger.
Radios that have different sets of batteries A and B or even a C were just called battery operated radios.
Sometimes confusing
MoeThanks for clearing that up Moe. So a “Farm Radio” is acually a type of battery operated radio.
I got the two confused as I can remember some of my relatives who farmed that had battery operated radios.
In the end, I guess what got bought for a radio came down to ingenuity (using the radio with what they already had on hand) and affordability.
Best,
GWS
Hi Gerry/Mr Moe,
Yes, I guess that is correct – one definition of a ‘farm radio’ is that they are a subset of the ‘battery radio’ class. I would say that if we are being pedantic, such a radio would include a vibrator power pack to convert the 6v, 12v or 32v to a suitable high voltage for the B supply – I have one or two in my collection like that, eg. Zenith ‘cube’. However, the term ‘farm radio’ is generally used to encompass battery operated radios, even if they relied on high voltage battery as the B supply.
Well I have the sequencing control circuit for this up and running. This powers the tubes up and down in a controlled fashion to get the maximum life out of them.
Right now I am using a Basic Stamp 2 as the controller but might migrate the control platform to a PIC 16F84 the like.
So the eliminator is going to have a really neat amount of technology in it.
Regards,
Gerry Shand
780-910-7031I now have a schematic now roughed out that I can start breadboarding the prototype from. This project is going to require a few power supply components I have never played with before so it’s going to be fun and interesting times.
I also want to make this supply universal enough where it can be used in any vacuum tube design whether it be a retrofit or a scratch design.
Now to come up with a name for it. I am thinking of the SSP-1 (small, sweet and powerful). The -1 denotes the maximum plate voltage design for 170 VDC.
Looking forward to seeing the final design Gerry – power supplies for farm sets and the 1920’s battery sets are always popular construction items. I have several such sets that need power supplies (I have to connect each one up to my one power supply when I want to use it) – it would be good to make a few such supplies so they could always be connected rather than having to fiddle about with connections each time (and risk making a mistake!). So make sure its cheap to construct…
Thanks
Ed
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This reply was modified 1 month, 1 week ago by
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So just a general question: what would you expect to pay for an item like this? Let me know your thoughts please. Thanks.
Update: I am having a setback getting the filament power supply to function. Getting a lot of heat. So trying a few other topologies to see what I can come up with as an alternative.
Today the filament power supply is prototyped and working!!! For the past 24 hours it has produced 1.5 VDC at 3 A. The next load test will be 12.6 VDC at 3 A. The primary pass transistor gets very hot but has not gone into thermal shutdown – so it only needs a bigger heatsink. The one I have was what I had laying around in the lab. Now to get all the PCB components onto a circuit board.
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Great job, Gerry! I love the look of all that spaghetti! I don’t understand it but I love the look of it! I’m with Ed on this. I need a couple to keep from screwing up the connections, too. Just figure out what the parts cost and what your time involved is worth to you and let us know what the charge for one would be.
Hey Robin:
This is just for the filament supply. I need two additional supplies for the B and C voltages, an interface board to prevent ka-booms due to bad connections, and a sequence control board so the radios are brought up and down nicely so the tubes aren’t stressed necessarily. So lots of work still to be done. And most of this spaghetti will migrate to a PCB – it’s easier to fix a prototype problem with spaghetti than it is to make a board and find your design has issues (been there, done that). So stay tuned to this thread for any updates.
Yeah – what sort of car is that Gerry? – looks like one of the old UK ‘Invalid Carriages’ – per the photo below (just kidding). I bet it is some rare Messerschmitt or something.
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Hi Gerry and Robin:
The vehicle is a take off of the Gizmo EV that was produced in the northwest United States. The frame and shell are fine but the DC drive system needs to be upgraded to an all wheel drive using AC variable frequency drives and the steering mechanism needs to be changed to a motorcycle handlebar arrangement. It is closer to a Peel Trident P-50(?) but much heavier due to the battery bank.
Regards,
Gerry Shand
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