need help with lm317 driver

[pumie3]

here is a better pic

 

[jaycey]

is that resistor red, grey, black? if so its 28ohms, Im no expert but if that is the case I dont think it will give you enough power for your diode.

On my blue ray PHR I use a 10ohm resistor giving me 125mv and on my LOC red I use 3 10ohm in paralel which I have set at 380mv (with more to spare)

 

[pumie3]

it is : red, grey, purple, silver, brown.

 

[pumie3]

recieved my rechargeble cr123a + charger today. But the batteries dont fit in the charger, its for 14500, 18500, 18650 etc. batteries. can i make the cr123a batteries longer with magnets or something so they fit in the charger and i can charge them without exploding or something?

 

[HIMNL9]

From the pic, it seem 2,86 ohm 1%, but i'm not sure.

Perhaps connected right, but can't say what's wrong.

Sure that there's no short circuit, right ?

Also, you used the trimmer in serie to the resistor ..... this trimmer appear to be (at first sight) an 1/8W one, and if the current through it is too much, it can be burned (it's very easy burn trimmers with also just mid currents)

Try one thing, not using trimmer, use just resistor for test ..... with just that one, you must read approximatively 430 mA, if you have a different one, like, 3,3 ohm, or 4,7 ohm, that are common values, just for check if the regulator works ok. (3,3 ohm must give, as example, almost 380mA)

But keep in mind, they also have to dissipate power ..... as example, with 430 mA, the resistor dissipate more than half watt, so you need to use an 1 watt one, for not cook it in short time.

Anyway, with this type of trimmer and connection, i'm convinced that, basically, if the regulator is still working, you just fried the trimmer.

 

[pumie3]

it was the trimmer, i just checked with 12V to see if it is working again and after 2 sec. there was smoke coming off the trimmer! So im now removing the trimmer and see if i get around 430mA.

 

[pumie3]

when i connected it, my resistor was smoking instantly, it was 0,6W. the highest watt resistors i got are 1W 1Ohm.

 

[HIMNL9]

As i said, too low ..... if you have some resistors, you can parallel them, just for the test ..... after all, 4 resistors of 1/4 watt in parallel, make 1 watt

and for the value, use all of the same value and divide by 4, like, 4 of 12 ohm = 3 ohm = 416mA ....., 4 of 15 ohm = 3,75 ohm = 333 mA ..... 4 of 18 ohm = 4,5 ohm = 280 mA ..... and so on.

BTW, that resistor looks 1/4 watt too

 

[pumie3]

i used 3x 10Ohm 0,5W resistors, so thats 3,3ohm 1,5W. I got a reading of 1220mA! After 4 sec. my resistors began to smoke. But i only got 1,38V over the 4 diodes.

 

[rog8811]

It looks like you have used second hand components, for testing purposes take out the cap and the diode to see if the circuit works with just the resistors and a test load.

Regards rog8811

 

[pumie3]

I'm not using second hand components. I did what you said and my measurements are: 4,8V and 620mA on the test load. i connected it to an 12V adapter. I used 3 10ohm resistors in parrallel on the Lm317. Is this good?
And one more question, when i hold the + - together i read 1,4ohms on the MM with nothing connected. So when i am measuring the resistance, do i have to take that 1,4ohms off? For example, when i measure the resistance of an 10 ohm resistor, i got a reading of 11,4 Ohm. So thats 11,4-1,4=10 Ohm right?

 

[HIMNL9]

1,4 ohm for the leads alone, is a too much high value ..... or the DMM is not precise, or the leads are damaged or make bad contact in the plugs.

Anyway, basically yes, take away the resistance of the leads ..... but i repeat, 1,4 ohm is decisely too high ..... my 5 euro "battlefield" DMM p) measure 0,4 ohm, and is the worse one of the 5 i have around (i use it just for see if there's voltage or continuity test, so no precision required )

The Beckmann ones measures 0,1 ohm, sometimes 0,2, but considering that one of them have 15 years and the other 8, is not too bad ..... and the new ones, goes usually to zero, sometimes 0,1 ..... ofcourse, there is always some tolerances, but, really, 1,4 for two pieces of wire, make me think about some bad contact / oxydation ..... or "cooked" DMM (ehm, you don't have measured some voltage or current with the DMM in ohm position, right ?)

 

[pumie3]

ok. It is a cheap voltcraft VC-11, also for 5 euro.
Recieved a new 20x sled from HTD today, so i want to finish my driver and install it.
I did what rog8811 said, so how further now?

 

[pumie3]

I used an 10 ohm and an 3,7 ohm resistor in serie. And im measuring 380mV over the 1 ohm resistor and 3,95V over the 4 diodes.
The potmeter didn't work. because i got 240mV what was too little and when i turned the pot a LITTLE and i got 720mV.
Is my driver good now to connect it with my 20x open can?

 

[HIMNL9]

I suppose you mean 10 and 3,7 ohm in parallel, right ? .....

This mean 2,7 ohm, that must be 460 mA ..... if you read 380, maybe your DMM is not precise ? ..... or the power supply is too low, like 5 or 6 V ?

Do a test on your DMM if you want, i suppose you're using the 2V scale, so, try to measure a 1,5V battery, and see what you read (use a new one) ..... alkaline must be 1,6 - 1,7V, if full charge, if you measure too much less, the DMM have some problems.

Or, also better, if you have a led, connect it to a power supply (9 to 12 V) with a 10 or 15 kohm resistor, then measure the tension on the lead of the led ..... leds have usually a very stable FV, at low currents, i used them in the past as voltage references, when the real VR chips was costing a lot ..... as example, a common 3mm red led, at 1 or 2 mA, have a very stable FV of 1,56 / 1,57 V.

 

[pumie3]

no, in serie, so i have 13,7 ohm. I used a 8,5V power supply
I'm measuring 1,90V on a new alkaline AA battery. I dont have LEDs here.
And can I charge cr123a battery's with an 14500,17500 etc.. charger if i make the cr123a's longer with magnets or something?