Ok, I think many are missing the main point of the thread. To many ppl had these and they didn't work. So, I found out why and posted the way they did work, the range , including a table of what to expect. Remember, I used a diode from Vcc to the "TTL" so it came "on" @ 3v - .7v(diode drop) = 2.3vdc to "TTL". It may turn "on" lower than 2.3vdc.
Vcc---------Voltage Out () Max Output (1mv = 1ma)
3VDC----------2.9VDC-----------27ma
3.5VDC--------3.1VDC-----------76ma
4.0VDC--------3.3VDC----------144ma
4.5VDC--------3.5VDC----------226ma
5.0VDC--------3.6VDC----------310ma
5.5VDC--------3.6VDC----------400ma
6.0VDC--------3.75VDC---------430ma
Is it a true TTL? No. If it were it would not turn "on" till 4.75vdc and any voltage over 5.25 vdc to the "TTL" should kill it. It doesn't. So, it appears to be driving the Base of a transistor or FET to turn it on and the output increases as the voltage increases.
Since I had Vcc always "dioded" to the "TTL" it may vary by just varying the voltage to "TTL" and having a max of 6vdc on Vcc. On the other hand, you may need to vary Vcc and "TTL" just keeps it on. Surely you can check this for yourself. I had it up to 8.4vdc on Vcc with a diode to the "TTL" so subtract .7vdc and that was putting 7.7vdc to the "TTL" and it did not die, but the output current was maxing at 6vdc. Above that its just converting the rest to heat on the output chip. It can be heat sinked with Arctic Thermal adhesive. Is it a modulated input? Well, I guess you could call it that if you have the pot set to max. Look at the table......3v gives you 27ma out and 6v gives you 430ma. So it will vary with diff voltage inputs.
The voltage out limits it to Reds, IR or a Green(actually IR) as this is abt all that will work at the listed output voltages.
I don't see where it that tough to look up the specs of the diode you are using, compare that to the table, and see if this driver will work for you needs. You can always dial the pot down to limit the max output ma for the input voltage you are using.
Hopefully this more clearly explains questions that have been asked.
It is what it is...a low cost driver for those not wanting to build one with a max of abt 430ma output. It is not a boost driver. You might compare it to a LM317 driver, but you'll need more parts than this costs. The LM317 could have a higher output if you needed it. Running multiple LD's ? What if one failed? Poof go the rest.
My apologies for adding to resurrecting the thread, but questions seem to keep coming up.
