Do I need Resistors across each diode?

[Meatball]

I'm going to be running two A-130s in series, off of an LM317 driver.

The current through the diodes will be monitored, and the Vf across each diode will be monitored as well.

I hear that it is good to put a high value resistor across each diode, to help compensate for PIV something or other.

And to do that, would kind of resistance are we talking about?

Will the resistors in place, affect the readings on the ammeter, and voltmeter?

Since I'm not too sure what the exact voltage drops across each diode will be a 1A, I'm not sure how large of a resistor I might look for. Would a 5W be alright?

Thanks guys!

 

[Fonduman]

should affect voltmeters etc, V=IR

 

[Meatball]

So... would a set of 100K Ohm resistors work alright? They might move the decimal point on the meters down a bit... how might I adjust that?

 

[Fonduman]

cant say about any technical stuff, im more into the fundamental physics side, and even that not fully qualified yet

 

[Bionic-Badger]

I haven't heard of putting a resistor for compensation in such a circuit. Are you sure that even does anything? The only place I've heard of adding resistors is for temperature compensation, but the LM317 already has temperature compensation circuitry.

If you're adding resistors so you can more easily measure the voltages, I'd use as high a resistor value as you can so you don't sap away current from the diodes.

 

[Fonduman]

if you are putting a very high value resistor in parallel with the diodes it should be fine. because the alternate (parallel) path will be of high resistance, very little current will go down it. voltmeters themselves for the most part are high resistance, if you were going to have the voltmeter in parallel with the diodes, I dont think putting a resistor in line with the voltmeter will cause much difference, although it might mess up your voltage values, best to leave it alone concerning that. a resistor in series with the diodes will reduce current through them and consume alot of voltage, making them very dim.