Capacitor values?

[chuzie]

Ok, so I broke 500. I didn't want to do it but I had no choice in the matter. I did last a few hours though!!

Anyway, I need someone to help me brush up on my electrical math.

I am trying to install a small capacitor inline or IC on the board of my radar detector to keep it from resetting each time I turn the key from ACC to RUN since it comes on automatically when I go to ACC. I can't find a good calculator for this so can someone chime in?

It is obviously on a 12V system and I measured the draw at 27mA. I have a fuse on the board (which I now need to order from Newark since I blew it today screwing around with the board) rated a 2A 125V so i can't have the capacitor discharging and blowing the fuse so we need to take that into consideration.

Any takers?

Thx,
Mike

[jollygrngiant]

Wow! uummm cratchhe: Sorry mike, can't help ya. Math and I don't get along very well.
Brian

[johnpaulgolf]

ok if you take the ohm reading of the flux capicitor and add it to the output of the amvolts and then divide that by pie and then add some caramel with a little coffee creamer you will get it.

P.S. don't forget the circuit does not break unless YOU F*** with it.

[chuzie]

Thanks JP. Couldn't have done it without you.

[Traveler]

I don't think you can do that with a capacitor actually.
If you can you need to ad a diode so it doesn't feed back and pop the fuse.

A capacitor is not a regulated discharge device. It simply stores the charge and dumps it as fast as it can based on resistance to ground, or load.

It may be as simple as adding a diode, but the capacitor size shouldn't matter it will never charge up over 12 volts, or 14 or whatever your battery voltage is.

The diode would prevent the capacitor trying to discharge immediately and basicaly supply the whole truck with power. It would essentially isolate the detector from the truck making it a seperate circuit.

[chuzie]

I have diodes on hand so that is not a problem.

So it will not store more than 12V in this case so that is good. What about dischage amperage? Don't want to pop my radar fuse.

BTW- I knew I was going to hear from Traveler on this one.

[blazinchuck]

I will take this up with my eng. crew at work tomorrow for ya...maybe they can help. I sure cant. But, I agree w/traveler on the results of each item mentioned,Chuck

[chuzie]

I actually considered a battery but I have no regulator to control the charging and do not wish the device to be on all the times the car is not, only during the brief moment between ACC and RUN which is when it has a momentary loss of power.

[blazinchuck]

whats so crazy about this??? Why is it important for a radar dect. to not reset between switches. what is reseting anyway. just wire it to constant 12v w/toggle switch to cut on and off and even wire in a 2 pin connector incase ya need to remove it.

[chuzie]

The power on BIT (built in test) initializes each time power is removed and reapplied to the unit and it is annoying because it does a lot of beeping. I could disable the BIT but that would defeat the purpose of having a BIT if it can't tell me if something is wrong with the unit. After all, I did pay about $350 for that thing.

Switches and stuff are for my Bronco project not my Wife's Honda Pilot. Plus I need something to do around this crap hole besides fly all the freaking time.