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Help with driver!

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bjarki93

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So i just got my diode from kendall @ hightechdealz.com
And i built a ddl driver for it.
My question is, when i measure the voltage on my battery it is 7.7V, but when i connect it to my driver the output to the diode measures 7.2V. I dont know why this happens and nothing is shorted out. Also i can't figure out how to measure the MA. The turning wheel on my DVM says: 200µ, 2000µ, 20m, 200m and 10A. on what setting am i able to measure 400ma? and can the lm317t overheat?

and don't point me to the search button or other threads!
thanks!
 





billg519

billg519

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Sorry, but the info you are looking for is in the forum. This has been covered many times in the forum. Unless you're very lucky, no one is going to spend time on this when you indicate right off the bat that you don't want to be bothered to search for it yourself. You might also want to google "basic use of a DMM" or something like that.
 
Asherz

Asherz

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Would it hurt to give him a clue? :)

Yes the LM317 can overheat, but it will feel hot to the touch and will not get anywhere near hot enough to burn out on a 9V battery, they naturally get really hot, that's what the heatsink is for.

To measure mA, it's something to do with a 1N4001 diode(s?) and a test load.

That's all I'm giving you :)
 
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bjarki93

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Thank you Asherz!
I just wanted the exact info on the driver since i could not find it anywhere!
And also my dvm is kinda small and doesn't show enough information!
 
D

Deleted member 8382

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The numbers on your multimeter indicate the maximum current you can measure on that position. Use the 10A mode to measure 400mA. Remember that you will need to connect the red wire to the 10A plug too!

Could you post what's the exact circuit you have build using the lm317 driver? I can't help you without that info. Regarding the driver overheating, it won't overheat if you use it properly ;)
 
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Deleted member 8382

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To measure mA, it's something to do with a 1N4001 diode(s?) and a test load.
Click to expand...

what? if he got a multimeter he can read the current directly! Again, please post the circuit you built, I need to see it in order to guide you...
 
ndrew2505

ndrew2505

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Asherz said:
Would it hurt to give him a clue? :)

Yes the LM317 can overheat, but it will feel hot to the touch and will not get anywhere near hot enough to burn out on a 9V battery, they naturally get really hot, that's what the heatsink is for.

To measure mA, it's something to do with a 1N4001 diode(s?) and a test load.

That's all I'm giving you :)
Click to expand...



measuring mA has to do with a 1ohm resistor... measuring voltage has to do with 1n4001 diodes... ;)

if your going to give something at least make sure its correct.. :)
 
bobhaha

bobhaha

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Also the reason the voltage dropped has a bit to do with efficiency and forward voltage. Nothing is 100% efficient and as such, loss in energy is inevitable.
 
Asherz

Asherz

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Well he got the idea, I just thought that if he searched for 1N4001 diodes, then he would come across a test load, and then realise that from that you can measure the voltage and current across a resistor :)

I got a little confused because he asked how to measure voltage and mA, so I was thinking off both when I posted.
 
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