TTL signal generator

[jkaiser3000]

I finally got around to puting together this experiment. Using the 74HC14 chip, a 2.2Kohm resistor and a 4.7 electrolytic capacitor I managed to blank my laser. According to the formula given it's supposed to have a ~10KHz frequency.

But even at that frequency my laser noticeably drops in power. I'd say it's puting out around 40-60 mw out of a total of 80 mw, so I guess this laser is not the best to have in a laser projector.

Well, I don't really mind, as I'm not planning on doing anything bigger than a living room .

Next, I'll try to use a pot to vary the frequency and see what I get.

[marconi]

Hi Jonathan,
That seems about right to me...
At 50 percent duty cycle (50 % on to 50 % off cycles of the input signal)
the laser will output half the rated power !!!
And, Depending on the response of the driver circuit
if the driver is limited to say 10khz, operating at a higher freq the output may go up or down because of circuit design and component choices used .
And may or may not be usable above 10khz..
Some will dim a bit and still be usable while others may not..

It also could depend on the symmetry of the waveform you are generating

Hope that helps !!!

[jkaiser3000]

I noticed a strange thing with this laser. At first I thought it was my eyes playing tricks on me :roll: . Unfortunately, that's not the case.

Once in a while, when running the TTL signal, the laser would mode hop, and convert into a TEMo1 beam. Usually, removing the signal would turn the laser into TEMoo again, but once it did not, so I stopped testing for the time being. I don't want to damage my laser y'know.

I don't know what's going on, I'll try to see what I can dig out

[psytron]

why not use the output from a soundcard (what ever frequency u want with a high degree of accuracy).the output from your line out is 1v if i remember correctly. so u use an op-amp to give u the gain u need.

using a sound program (simple oscilator would work) you supply the frequency.
if it is a good program u can use a square wave and alter the duty cycle (look up pwm)

next step it to hook up an oscillator to a power meter (perhaps a solar cell??)
to see how the lasers ttl performes at different frequencies.....

[jkaiser3000]

I carried out some more tests, this time with a simple design using the 555 timer chip found here http://www.ozitronics.com/docs/k111.pdf. I noticed the laser doesn't completely blank with the signals, staying very dimly lit when it's supposed to be off. Also, it keeps mode hopping, especially when the signal is injected with the laser on (turn the laser on, connect the TTL wires to the signal generator and then turn the generator on). If I turn the generator on and then the laser, it doesn't hop. When it hops it has two big dots side by side, and a dimmer and smaller one in between the other two, whatever that mode is :roll:.

Have you any idea why this could be happening? Anything I can do to remedy this? Could it be the powersupply that is not adecuate enough? or is the diode/MCA the culprit?. Maybe I'm putting too much current through the TTL wires, I'll try to use a resistor in series to lower the current and see what happens