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Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
I'm surprised that it works as drawn!
I'm suprised that the 74LS73 high output current is enough to drive the transistors. (by the way, to answer your earlier question, LS stands for "low power schottky", like normal TTL but faster due to internal schottky diodes preventing the internal transistors from saturating)
Add a 330 ohm to 2.2 kOhm resistor from each of the Q and /Q outputs to +5V you will get much a better output waveform.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hey, I'm really sorry for this. I could have done better than misreading the schematic and then moaning about it. The circuit will work as it was (with filtered supply, surely ), although with probably not much efficiency and practical purpose.
One of problems with 3055's is their heavily variable Hfe. It can be as low as 5, and this must be taken care of.
Registered Member #588
Joined: Sat Mar 17 2007, 11:06AM
Location: UK
Posts: 93
Marko wrote ...
Hey, I'm really sorry for this. I could have done better than misreading the schematic and then moaning about it. The circuit will work as it was (with filtered supply, surely ), although with probably not much efficiency and practical purpose.
One of problems with 3055's is their heavily variable Hfe. It can be as low as 5, and this must be taken care of.
I'm amazed it worked to, not many things turn out to work after I have designed them, I tend to break more than make! Changing gain... Hmmm what about feeding in a constant current pulse in each individual 3055?
Sulaiman wrote ...
I'm suprised that the 74LS73 high output current is enough to drive the transistors.
Add a 330 ohm to 2.2 kOhm resistor from each of the Q and /Q outputs to +5V you will get much a better output waveform.
Opps it is a SN74CH12N Flip-flop, not 74LS73.
Ive added a 330R in series with the 2K2 variable and it did nothing... and I added one on the Q and /Q FF outputs and it raised the wavefrom up, is this good? So it is biasing the driver transistors?
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
To answer your question "Ive added a 330R in series with the 2K2 variable and it did nothing... " (That's what I'd expect - no change)
"and I added one on the Q and /Q FF outputs and it raised the wavefrom up, is this good? So it is biasing the driver transistors?" (Yes that's good, the increased bias will allow higher current output)
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Inverter help
), although with probably not much efficiency and practical purpose.
