Help needed to locate petentiometer

[jaycey]

Hi guys, I have built a DDL driver for my laser and its working but my petentiometer is no good for the purpose (bluray diode)

I have a Maplins nearbye can someone take a look at their catalogue for me and point me to suitable items.

Here... http://www.maplin.co.uk/Search.aspx?menuno=12464

Thanks

 

[XCreedX]

Well, you will want a 100 ohm pot at the max, so just choose a trimmer, i like the square 22-turn pots, their small and very precise. That catalog doesn't offer a 100 ohm version though, so check the store and see if they have one, if not just pickup a 100 ohm trimmer.

 

[Asherz]

Hi,

Unfortunatly I'm in the UK so no radioshack But lasers arn't illegal here completely so I guess thats a bonus (touch wood)

I use either this in the 1k version: http://www.maplin.co.uk/Module.aspx?ModuleNo=2202

or this 100ohm single turn pot: http://www.maplin.co.uk/Module.aspx?ModuleNo=6499

The only problem with the 100ohm version of that single turn is that it's round and it's a pain in the arse to put onto a piece of strip board because the drivers designed for the square pots and I could never work out where to put the pins on the round one

Good luck.

 

[lasersbee]

Don't use a single turn 1000 Ohm (1K) pot... use a single turn 100 Ohm
pot or a 22 turn 1K pot or an 18 turn 500 Ohm pot for finer control of
the output current...

Jerry

 

[Asherz]

that one in the link is a 22 turn 1k laserbee do you know the pin config of a round pot in comparison to a sqaure pot? how would you use the round one isntead of the square?

 

[rog8811]

The thing to remember with the 1k multi turn pot is that all the adjustment is right at one end of the pot so go carefully.

First picture shows difference between 100ohm and 1k pot.
Second one shows single turn trim pot connection compared to multiturn.

Regards rog8811

 

[XCreedX]

Their basicly the same all you need to do is really connect the pins here are the diagram

9V simply means the PSU and if you use a switch well wire it before you hit the pot, basically your power is the middle pin and you can use either side pin, the side pins simply reverse current to either side. then take the side pin wire and run it to your motor or in your driver.

 

[XCreedX]

Rofl rog, i was just making a diagram and you posted that

 

[jaycey]

I fear I have killed my diodes....all 4 of them! (BluRays)

I picked up a 50ohm Sub-Miniature Fully EnclosedCarbon Preset Potentiometer

Hooked it all up with a 10ohm resistor and started turning it up...slowly (didnt have enough diodes for a test circuit!)

All of a sudden it went super bright and then dimmed and stayed like that, the 10ohm resistor gets very..very hot?

Now I still get a dull purple beam but thats it.

My setup is DDL driver, 50ohm pot as above, 10ohm resistor and powered by 11.1V 430mah LiPo

Any ideas why the 10ohm resistor is getting so hot?

 

[lasersbee]

That's a bummer....

Yeah... 4 Blu-Rays are definitely cheaper than 6 1N4001 Diodes (Test Load)...
Good choice... Sorry that the Test Load info hasn't been posted before...

Jerry

 

[jaycey]

hmmm...the laser is still lasing but only when the petentiometer reaches its furthest point, its either on or off nothing in between?

wander if it is the diode or the pot thats fried?

 

[jaycey]

couldnt get hold of any more 1n4001's I only got 4 not 6.

The blurays didnt cost me a penny...thats why I wasnt too bothered about them.

 

[rog8811]

Use one of the dead LD's as a load, put a 1ohm resistor between the driver and the positive leg of the LD and test the circuit, when you turn the pot you should get a smooth increase in mv up to 125mv, if it goes higher than that it will explain the hot resistor.
If wired incorrectly the LM317 can supply 1.5A which will kill any LD.

Regards rog8811

 

[BuildAbluraylaser]

Good source for electronic components : www.digikey.com