TTL Modulation

[Gryphon]

I just got my 1W 808nm labby from snoctony today and it works great with the exception of one thing, modulation. My only other labby also has modulation capablities but because i don't use it and 0V means full power i don't have any problems pluggin it in, turning it on and being happy. My new 1W on the other hand appears to be 5V for full power and 0V for off. So with this one i plug it in and the connect 4AA's to the modulation leads to get it going. The purpose of buyinhg the labby was to eliminate batteries but they seem to have made thier way back.

My question is, is their any way to trick the PSU into supplying full power all the time without the need of sending power in thru the leads?

Heres what i got just incase you'd like to know before answering
1W 808nm Infrared laser with analog +TEC+ Power Supply - eBay (item 130310027540 end time Jun-30-09 19:29:39 PDT)

 

[Hemlock_Mike]

The laser that "works" most likely has a pull-up resistor to the TTL input pin. TTL likes to sink volts rather than supply. There might be a regulated 5 volts in there and you can solder say a 4.7 K Ohm resistor to 5v and the TTL pin.

Mike

 

[Justin]

Have you tried simply shorting the modulation leads to themselves? If the two leads are touching it should work to fool the circuit into operating.

 

[Gryphon]

Have you tried simply shorting the modulation leads to themselves? If the two leads are touching it should work to fool the circuit into operating.

Nope, tried that one, it didn't work. I have noticed that if i hold the positive TTL lead with my fingers the laser powers up slightly :thinking:

 

[Gryphon]

The laser that "works" most likely has a pull-up resistor to the TTL input pin. TTL likes to sink volts rather than supply. There might be a regulated 5 volts in there and you can solder say a 4.7 K Ohm resistor to 5v and the TTL pin.

Are you saying i should prod around on the power supplies circuit board for a 5V source and simply solder the TTL's leads to that? I'll dismantle the PSU in the morning if thats the case and start looking. Thanks for the input

EDIT: Double post, my bad

 

[Hemlock_Mike]

Remember --- I said through a 4.7K Ohm resistor.

Mike

 

[Gryphon]

OK, just thought i'd make sure. Thanks again