TheSamba.com :: View topic - Judson Magneto

Tue Mar 18, 2014 11:28 am

OK so does the Judson Magneto add anything to the performance of your VW...maybe it does, maybe it doesn't.

I have a friend who back in the 1960s ran the Supercharger Department at Conshohocken and this is what he told me about the Judson Magneto...

Quote: What it is, in its last and permanent form is as follows:
Very high output GM ignition coil, wound ,and dipped in sealing wax, and checked for high voltage on an oscilloscope up to 6,000 rpm & 40,000 dc volts. Coils are then placed into a thermo-plastic base, secured by a self tapping screw into the coil wire base. The original design had a small circuit board and a circuit consisting of a real transistor, a zanier diode and some small electronic devises, all of which failed too quickly. Construction: Coil connections were soldered, heat sinks were pressed onto coil bases, epoxy was used to seal the unit. Hot tar was poured into coil and circuit, a rubber gasket and a thermo-plastic cap was screwed on. Then back to the oscilloscope for final testing.

Did it work ?? Was it worth it?
YES, and YES again !! Compared to stock coils, and if you knew what to look for, this simple but effective coil ignition did all that could be done at that time.
Stock coils tend to die off around 5500 rpm, the Judson kept firing strong at 6250 rpm. This was verified on an oscilloscope, a supercharged Corvair, a turbocharged Corvair, a modified Falcon Sprint and a race prepped Falcon Sprint.
The problem with introducing a new performance product is the scrutiny it comes under, does it work ? does it do what it should do ? is it worth the money ?
The finished product retained the transistor, but did not have it wired in, the circuit board was eliminated, the diode was retained and was wired in. In this form it retained its electronic standing, and if you took your car to redline, it kept firing. Did it slam you back in your Recaro ? NO, it's not supposed to. Did it help you win races ? Yes! So, was it worth it?

So in the early '70s it was called a fraud. Personally I don't think it was. It was an honest attempt initially to produce a reliable high performance coil, using the technology of the day. Unfortunately a small company having spent a large amount of capital having the shells of this smart performance coil made, found the components used couldn't stand the temperatures produced and it broke down very quickly. With all the smart jackets lying around they found the best and most reliable high performance coil available at the time and bought them from GM by the box load...the best solution in what could have been a financial disaster.

If you have a Judson Magneto and it runs well it's pretty certain you have the modified version. Most of the early failures were returned and thrown away. I had one on my Beetle and Ghia for years and they have performed faultlessly. So it's not transistorised, hardly a fraud in an age where you could get away with a lot worse in advertising. :)

Sat May 24, 2014 4:52 pm

John Moxon wrote: Yes the Judson Magneto can be used on 6 or 12 volt...no difference in the unit. However if using on 12 volt you should fit a balance resistor. The Ballast number given by Judson is obsolete, but your local electrical parts supplier should be able to cross reference it. Does anyone know if a Judson See/Dee requires a ballast resistor if used on 12 volt?

Sun May 25, 2014 3:26 am

Jacks wrote: John Moxon wrote: Yes the Judson Magneto can be used on 6 or 12 volt...no difference in the unit. However if using on 12 volt you should fit a balance resistor. The Ballast number given by Judson is obsolete, but your local electrical parts supplier should be able to cross reference it. Does anyone know if a Judson See/Dee requires a ballast resistor if used on 12 volt?

No it doesn't need one: https://www.thesamba.com/vw/archives/lit/judson/in...ctions.pdf

Sun May 25, 2014 6:49 am

Very helpful. Thank you. :D

Thu Jun 12, 2014 5:25 pm

I bought one in about 1967 and put it on my 1961 Chevrolet . I could see no difference in performance or gasoline mileage , it did burn out during the first few months and left me by the side of the road . Luckily I had the original coil in the trunk .

To this day I carry a variety of small part spares in my VW's .

Wed Dec 28, 2016 1:59 pm

Back in the 70's I took one of these apart and found it was a fraud! The uppser device is a stud diode, that is connected in series with the coil. The emitter and base of the T03 transistor aren't connected to ANYTHING!

Thu Dec 29, 2016 1:02 am

Takeda2 wrote: Back in the 70's I took one of these apart and found it was a fraud! The uppser device is a stud diode, that is connected in series with the coil. The emitter and base of the T03 transistor aren't connected to ANYTHING!

Yes...see my post at the top of this page: http://www.thesamba.com/vw/forum/viewtopic.php?p=7115187#7115187