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Triggering TTL on driver. 5V signal

Seoul_lasers

Seoul_lasers

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Alright, so I am building, or have built a 445nm driver housing using Die4driver v1.3 board.
I am adding 6 contacts for my lab laser. 2 for power in, 2 for current monitoring and 2 for TTL. However with regards to properly utilizing a TTL, I will shamefully admit I am not so familiar.

Does someone here know how to use the TTL and make a pulser for it or get one if possible? I can use the driver in 2 mode, but TTL would be nice.


project driver enclosure will look like this.

|x| |x| pwr |x| |x| current monitor |x| |x| TTL
 
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A

anselm

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First thing to do would be to figure at exactly what voltage the Die4Drive's TTL activates.
TTL usually is 0V low and 5V high, but the threshold could be very well anywhere in between.

Then I'd suggest you look into the LM555 IC.;)
Seems like the most simple and cheap way to generate signals.

I've never used one though.
 
DakotaDaNative

DakotaDaNative

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the output of the 555 is always going to be slightly lower so you might have to run the 555 at about 8 or 7 volts im thinking? a good way to check would be to build it then get a meter and vary the power to the 555. i think the operating voltage is something like 5-18 volts but im just talking from memory. oh and it might be smart to consider that a 555 in astable mode is a really cheap PWM so at higher frequencies you might not be able to get a 5v output pulse.
 
123splat

123splat

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It depends on what the driver really wants to see as a 'TTL' signal, but the standard is anything above 2.5 volts is a TTL logic 1, anything below 1.5 is a zero, anything in between is 'unknown and can/will produce unpredictable results'. A 555 will do the trick admirablly (cheap and easy to setup).

A question: do you really want to modulate with TTL, or do you just want to switch on and off ? If you are just switching, a simple switch to the + rail may do the trick.
If you intend to actually modulate or to switch with other TTL circuitry, direct drive from the TTL output will probablly work fine, but you can buffer through a couple of nand gates, or something similar, to be safe.
 
Seoul_lasers

Seoul_lasers

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123splat said:
It depends on what the driver really wants to see as a 'TTL' signal, but the standard is anything above 2.5 volts is a TTL logic 1, anything below 1.5 is a zero, anything in between is 'unknown and can/will produce unpredictable results'. A 555 will do the trick admirablly (cheap and easy to setup).

A question: do you really want to modulate with TTL, or do you just want to switch on and off ? If you are just switching, a simple switch to the + rail may do the trick.
If you intend to actually modulate or to switch with other TTL circuitry, direct drive from the TTL output will probablly work fine, but you can buffer through a couple of nand gates, or something similar, to be safe.
Click to expand...

Already have the lab driver set up that way. + TTL to + rail = high current mode @ 1.865A or about 2.1W.
I was hoping to pulse the diode at 20Khz or even 50Khz to conduct some experiments.
 
123splat

123splat

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Understood, and a 555 oscillator (astable multivibrator) circuit will do the job admirablly. R*C time constant is used to set frequency, so you can use a pot to have a variable frequency, or switch select multiple R or R*C values preset to desired frequencies. As with anything else, there are always many other ways to accomplish the desired results (you could e also use a Hex Inverter and some resistors and capacitors to make a TTL level oscillator, but the 555 is lots more versatile and forgiving).
 
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