Why won't my driver work?

[spinout059]

I am using a senkat diode.
A 10k multiturn pot
LM317T + volt Reg
10 OHM resistor 1/2 watt
1N4001 silicone diode
47MFD 35VDC capacitor
two CR2032 energizer batteries each rated for 3v, not used before
And a momentary switch in between

I have an analog multimeter but I cannot get it to work...

I hooked it all up according to daedal's thread and was greatly releived to see my laser come to life!
It was a VERY dim light so I turned my pot, nothing happened... turned most possible both ways, still the dot was extremely dim.

I tried it with a 10ohm 1/4 watt resistor and still same thing

If needed I have a 1K multiturn pot here if you guys think I should try it.

I got my parts from radioshack btw.

Here are some pics

Any help is greatly appriciated, if I need different parts what are they?

 

[desslok]

Put a 1ohm resistor in series with the diode so you can meter mA going into the LD. THen while metering, adjust your trim-pot. You should be using a 100 ohm trim-pot BTW, as the 1k will give you a VERY small adjustability range. You should get an adjustment range of ~1 mA to ~400 mA +/1 25 or so. If you aren't, meter across your trim-pot and see if it's in spec, you should be getting single digit ohms. Then meter across the trim-pot AND resistors (FYI make sure resistors in parallel so they are 5 ohm), and you should get 5 + trim-pot's value, so say 7 ohms across both, if your trim-pot is at 2 ohm.

IF this isn't working, go back and re-solder everything very carefully. A cold solder joint can put too much resistance and make it not work. If it still doesn't work, you may have overheated a solder joint and internally melted a component, such as the trim-pot.

The best way to test is with a dummy load, like the 5 diodes in series and the 1 ohm resistor.

 

[chido]

The thread for testing the circuit is here:
http://www.laserpointerforums.com/forums/YaBB.pl?num=1197651171
And don't use a 1/4 watt resistor, use one that is at least 1/2 watt. Also don't use just one 10 ohm, try to use two 10 ohm resistors in parallel. That will limit the current to 250mA. Oh, almost forgot, use the 1k ohm pot, instead of the 10k. For every turn of the 10k it's about 1000 ohms, compared to 1k which is about 100 ohms per turn. If you don't mind space, buy the 25 ohm rheostat, that way you'll be able to make more accurate adjusments.

 

[rog8811]

Just a word to the wise here, you have the circuit board upside down, the components should go in from the non-copper side, done correctly you will then be soldering the wires to the board as well as each other and things won't be able to move.
There is a possibility that, with the way you have done it, that there may be a solder short across the pads in amongst the components, also there is little mechanical support to the wires.

Regards rog8811

 

[amkdeath]

um dood ur using a button cell battery, thats not gonna work.

u need at least 6v too
Get a 100ohm trimpot from ebay for 1.75 for ten of em. They are smaller than the current pot ur using too.

I thought I was a messy solderer, dood, clean it up, u might, wait no u are shorting something there without knowing. get a new PCB, and try using minimal solder. also, when u use a PCB try not to use wires, put the things that need to be connected near each other, and solder leads onto the little copper thingys. let the copper thingys act as wires. they sell a etch ur own pcb kit at RS too, that might help in the future

 

[rog8811]

um dood ur using a button cell battery, thats not gonna work

I didn't get as far as noticing that amk is absolutely correct, no where near enough ma out of button cells to drive a red and the voltage will sag under load.

If you look at the second post of the above link, posted by chido, it shows where to measure the ref voltage. I will guarentee that it is not 1.25v and that means you do not have enough voltage to get the regulator working.

Regards rog8811

 

[spinout059]

um dood ur using a button cell battery, thats not gonna work

I didn't get as far as noticing that amk is absolutely correct, no where near enough ma out of button cells to drive a red and the voltage will sag under load.

If you look at the second post of the above link, posted by chido, it shows where to measure the ref voltage. I will guarentee that it is not 1.25v and that means you do not have enough voltage to get the regulator working.

Regards rog8811

ok so even though they are rated for 3v each they will not work?

 

[rog8811]

ok so even though they are rated for 3v each they will not work?

ma's is what is required and a red LD needs more of them than those batteries will provide.

I know it is a different scale but think of it this way, you have a car and a motorbike, they both have a 12v battery to start the engine the car one is 4 times the physical size of the motorbike one...the reason the motorbike battery will not start the car is not enough amps output even though it is the same voltage...

Did that help???? :-/

Regards rog8811

 

[spinout059]

ok so even though they are rated for 3v each they will not work?

ma's is what is required and a red LD needs more of them than those batteries will provide.

I know it is a different scale but think of it this way, you have a car and a motorbike, they both have a 12v battery to start the engine the car one is 4 times the phisical size of the motorbike one...the reason the motorbike battery will not start the car is not enough amps output even though it is the same voltage...

Did that help???? :-/

Regards rog8811

YES! Thank you rogue and amk! The batteries were deffinately the problem. I am connected to 4 AA's now and i got the diode to powerup, then one of the wires broke off the pin and has to be resoldered. But my soldering iron broke. Ill go get another soon but first. I have an analog radioshack multimeter with 8 settings (DCV 15, 150, 1000, RX1K, 150ma, ACV 1000, 150, 15) which should I be on?

 

[rog8811]

If you are testing as described in the testing DDL's circuit thread you need to be on the DC 15v scale..... measure the ref voltage first you need to be at 1.25v.

Regards rog8811

 

[chido]

Use at least 6 AAAs nimh, if you use alkalines they will sag very quickly. Read this thread, it has info about using 6 cells nimh: (start reading at post 701)
http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612/701#701

 

[spinout059]

Use at least 6 AAAs nimh, if you use alkalines they will sag very quickly. Read this thread, it has info about using 6 cells nimh: (start reading at post 701)
http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612/701#701

What abotu using 2 cr123's?

 

[rog8811]

What abotu using 2 cr123's?

Perfect

Regards rog8811

 

[Gazoo]

Nope...they sag too and it has been confirmed. The best solution is 6 nimh batteries, or 2 li-ion batteries. A pair of RCR123's would be just fine..

 

[spinout059]

Nope...they sag too and it has been confirmed. The best solution is 6 nimh batteries, or 2 li-ion batteries. A pair of RCR123's would be just fine..

Ok so I buy a pair of rcr123 and ill be ok? ( i want my laser to be a bit small)

 

[rog8811]

Nope...they sag too and it has been confirmed. The best solution is 6 nimh batteries, or 2 li-ion batteries. A pair of RCR123's would be just fine..

I hate to differ with you gazoo , but I have had very good life out of the CR123's with my red.......though I am not trying to wring the last mw out of it.....

Regards rog8811