sorry mate, must have made a mistake somewhere....i managed to invert the signal from the 555 using the inverting buffer (bjt)...also the two signals are 176 degrees out of phase instead of 180, which means that during the run (at a certain point and time) all four switches are open....
sorry mate, must have made a mistake somewhere....i managed to invert the signal from the 555 using the inverting buffer (bjt)...also the two signals are 176 degrees out of phase instead of 180, which means that during the run (at a certain point and time) all four switches are open....
hi,
Pleased to hear you are making progress.
Its the transistor invertor thats causing that 176deg problem, a comparator, used an invertor could could be set to give a switch over near 0Volts, in order to give 180deg.
ok we made this really big circuit....with three 555 timers - one of them providing the clock for the other two
with the other two we can vary the duty cycle and make it work.....this is still in progress as one timer give 70% (as we want) and the other is giving 1% (we want 20-25%) - i tried changing the values of the resistors and capacitors .... anyway this problem is being worked on....
your idea of having two pnps...i have tried it in pspice... i will post it soon
hi,
I agree, I would have thought his simulation program would have burped and thrown up a warning... the 'base' voltages, wrt 0V, on the reversed transistors should have been an indication.
legs drive 2 transistors only at any time
now worry. please take care of base current needs by managing the series base resistor.
555 has adequate capacity.
well its done....a 555 timer with an inverting buffer driving four NPN H-Bridge...it didnt work the first time coz of the base resistances...and also becoz the inverting buffer had popped (the second time)...so my 12VDC power supply showed a short circuit