UPDATED 1/2/13
When I got the A.R.C. Type 12 Radio Set working, I did not have a suitable dynamotor, let alone the correct one, a D-10A. Anxious to get it going for upcoming hearability experiments, I designed a simple solid state power supply that plugs into the 3 pin connector on the rear of the R-19 receiver in place of the dynamotor. In the A.R.C. Type 12 system, that dynamotor powers both the receiver and transmitter.
SS Dynamotor interior
The mechanical mount needs to be reworked as this is really a circuit design prototype, but the power supply runs the receiver and transmitter quite well. It puts out the required +250 VDC at +13 VDC input producing only 0.5 volts ripple.
The oscillator frequency is about 25 KHz to make the transformer and filter small and simple. It runs at 80% efficiency which is not great but I have plenty of 12V battery power available for the application..
That oscillation frequency is well above the bandwidth of the audio circuits (as well as my ears) so it is inaudible while running, either acoustically or electronically. It runs only slightly warm and not bad for a first attempt.
With the minibox cover in place the radiated switching harmonic noise is minimal and not heard in the receiver output on the VHF aircraft band.
Solid State Dynamotor prototype – N6CC
Above: Built in a minibox, using a balsa wood “connector” and three brass sleeves for contacts to the receiver dynamotor connector. Works well enough for circuit testing.
A.R.C. Type 12 Solid State DIY Dynamotor
It will also run a Command Set receiver although the voltage is too high for those radios. I will build another one with a reduced number of secondary turns for about 220 VDC or less output for those.
The key is the ferrite transformer and it uses a 3B9 core that I had in my junk box – it may be hard to exactly replicate with a different core (and material). A little experimentation will make it happen. I’ll try to find a suitable replacement from parts available these days and then evaluate a design based upon that. Stay tuned…(but not done as yet!)
AR
Hi Tim
I would like to inquire for the state of the project
kind regards
Peter (HB9RUZ)
Hi Peter – Since this circuit worked so well for me I did not improve it beyond that shown in the Post.
I see that I did not include the final schematic of the little 220V power supply for the Type 12 set. However the 100 volt supply I built for my GRC-109 is essentially the same but it has about half the secondary transformer turns. You could double the number of turns OK..I am not sure if this ferrite transformer core is still manufactured but it would be a good place to start. The Ferrite material is 3B9 [correction]. Since the supply would be operating from a big vehicle battery I was not too concerned with efficiency – hence the simple resistor drive circuit for the oscillator Base drive..Take a look at my GRC-109 circuit here for a starting place:
http://www.n6cc.com/grc-9-grc-109-receiver-battery-power-supply
Cheers! Tim
N6CC
What value RFC’s did you use in your GRC-109 transmitter and receiver battery power supply. No values were referenced. I’m building a power supply so ai can get my ARC-5 setup on the air.
Thank you in advance for your reply!
Respectfully,
Phil
Hi Phil – I think you are referring to the article I wrote on the GRC-109 DC power supply that I built (not the above). In any event I forget exactly but they look like standard 1 to 2.5 millihenry RF chokes of appropriate current rating. I used what I had in my stock, the actual values are not critical as long as they can handle the current. Maybe not even necessary in that design but “good engineering practice” in any event. I’m not sure what is available in today’s components market but they are nothing really special. You could even wind some on a ferrite torroid core. Good luck with your ARC-5 project & thanks for visiting! Tim
Tim,
What perf board did you build the solid state dynamotor on? Looks like it has side tabs for inputs/outputs or power source. I’d like to buy some of those proto boards.
Phil
Hi Phil – Wow, straining the brain on this one! I think I got a few from a guy at a swap meet who had some DEC (Digital Equipment Corp – remember them?) prototyping boards that fit their motherboard/card cages. They might have been custom OEM-type boards from DEC. Sorry I don’t remember the details but it was handy for the application. Pretty much anything would work here but this one fit the box!
A fun project, thanks for visiting…Tim