Voltage regulator capacitor value?
 

I am in need of the value for the capacitor (condenser) in the base of the Bendix/Eclipse plug-in voltage regulator as used in the Sexton, and other Sherman variants. Both mine are bad, a well as the ones at the museum. I probably have one, but just need to know the value. Jesse.

Hi Jesse..
I don't know the value ..But here is some info..and paralleling capacitor will help and adding a heat sink will help to dissipate any heat.


the component has three legs: Input leg which can hold up to 36VDC Common leg (GND) and an output leg with the regulator's voltage. For maximum voltage regulation, adding a capacitor in parallel between the common leg and the output is usually recommended. Typically a 0.1MF capacitor is used. This eliminates any high frequency AC voltage that could otherwise combine with the output voltage. See below circuit diagram which represents a typical use of a voltage regulator.





Note:

As a general rule the input voltage should be limited to 2 to 3 volts above the output voltage. The LM78XX series can handle up to 36 volts input, be advised that the power difference between the input and output appears as heat. If the input voltage is unnecessarily high, the regulator will overheat. Unless sufficient heat dissipation is provided through heat sinking, the regulator will shut down.


http://www.eidusa.com/Electronics_Voltage_Regulator.htm

Alex; Thanks for the information. Anyone have any printed information on the regulators, or a way to cross reference the part number for the condenser? Jesse.

Reg Cap
 

Hi Jesse,

Am I right in thinking you don't mean a 78XX/79XX voltage regulator, but one from your Sexton similar to the pic attached??

Alex McDougall

Alex; You are exactly right. The circled item is the culprit. Do you have a tester? I wonder if all of them are bad after 65 years. Most of the capacitors on the WWII radios are still good. A few types, and manufacturers, though can be expected to be bad. Jesse.

Regulator base Capacitor (Condensor) value
 

Hi Jesse,

1 uF (Microfarad) for the General Lee/Grant Medium M3 Tank.

See pic for confirmation - sorry about the poor quality.

Alex

Thanks to both Alex's for the solution to my problem. While we are on the subject, the voltage regulator I have from another vehicle fits loose in the base. There doesn't seem to be an adjustment for this. Any one ever add shims to one or the other side? Jesse.

Cap tester
 

Jesse
To test the capacitor,take a analogue ohm meter..One with a needle..not a digital..
Turn the ohm meter to the highest resistance and hold one lead to the output lead and one lead to the case(Ground)
If The capacitor is good,the needle will jump halfway up the scale and slowly fall back towards zero...
What is happening is the capacitor is good and is being charged to 1.5V or the ohmmeters battery strength..
This means the cap is good..
The capacitor is only good or bad..There is no in between..
To recheck..reverses the leads and the needle should jump again and repeat the charging,but with the opposite polarity.
ALL capacitors can be tested this way..I been doing it for 45 years and it works fine..
The capacitor size for both magneto and spark coil capacitors range from 0.2 microfarad to 0.33 micro farads. Almost all automotive distributor coils use a 0.25-0.29 microfarad capacitor.
Add a heat sink around the case to get rid of excess heat.
You do great work so any little help I can offer..I'm in..
By The way ..the capacitor acts as a voltage ground bleed and minimizes the arcing at the points when they open and closed, but its main function is to provide a circuit path for the coil after the points open and to speed up the collapse of the magnetic field..
You can really burn the points out when the cap fails.
You can also parallel the caps to give you longer use and better heat control..but hook them up with like polarity or they will burn out instantly..
Values of capacitor and equal to the total values divided by the number of caps in parallel. ...so 1 micfarad + 1 micfarad in parallel = .5 microfarad..or just where you want to be.
Here are the formula and some explanation..I find all this shit after I type all this out..
http://www.electronicrepairguide.com...apacitors.html

Here is a good explanation and a good simple wiring diagram .
Draw another Capacitor identical beside the one pictured in the wiring diagram, connect the leads and ground the case,shown as ground symbol and away you go .

http://mgaguru.com/mgtech/ignition/ig108.htm

After writing all this I found this..It never fails..

http://www.smokstak.com/articles/capacitors.html

Read this and you will be the smartest capacitor guy in Indiana.
(Except when I'm in Zionsville)

Alex; Great information. I used to spend a lot of time restoring the old tube radios; before the armor came along. I was trained in electronics in the USMC in the early 80's. Fascinating stuff, the old tube radios, especially the military sets. I have a tube powered capacitor tester. It's really ancient, but works perfectly. Jesse.