# delayed pulse circuit using 555 timer for triggering two (1 and2) quadrant chopper

Discussion in 'General Electronics Chat' started by uskamera, Apr 7, 2012.

1. ### uskamera Thread Starter New Member

Apr 2, 2012
2
0
hi everyone
i am trying to make a two quadrant chopper (1st and 2nd) for this i require triggering pulses for two switches t1 and t2 ,both having duty ratio of 0.25 and pulses of t2 should be delayed by T/2.
Is it possible to generate the gating pulses using 555 timer circuits. Any help is welcome. if something is unclear regarding above topic please ask.
THANKS ALOT

2. ### jimkeith Active Member

Oct 26, 2011
539
99
I would drive a 4013 D flop with a 555--then drive two more 4013's with Q & /Q (tie /Q to D on each).
This provides a two phase square wave (quadrature) at 1/4 the freq of the 555.
Then use two 4001 OR gates to generate the 25% duty cycle you need.
This takes three more chips, but they are very inexpensive and require no other circuitry.

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3. ### uskamera Thread Starter New Member

Apr 2, 2012
2
0
hi jimkeith
thanks for one option using flip flop
can you put some light how this can be done using monostable and astable multivibrator with delay circuit....... any diagramatic help will most useful
THANKS

4. ### jimkeith Active Member

Oct 26, 2011
539
99
circuit coming

5. ### jimkeith Active Member

Oct 26, 2011
539
99
This is the promised schem--yes it is not difficult to do with 555s--not as accurate timing as with flip flops as I first described, but functional.

I have provided approx resistance values--you must select cap values for your timing and further adjust resistors.

R2>>R1 so that U1 output pulse has good symmetry

R4>>R5 so that monostable resets quickly and pulse width is more stable

C2 couples negative going edge of U1-3 to the trig input of U2

D1 shunts the positive going edge of U1-3 to the positive rail to prevent potential malfunction in U2

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