components value in given diagram

BradtheRad said:

This looks like a bistable multivibrator. You have more than one input to make it change state.

The toggle input might be tricky to make it work right. The circuit needs to be adjusted carefully, so it can be toggled to the opposite state by a toggle pulse, whether it is presently in the Off or On state.

Component values are similar to the classic astable multivibrator. I think R3-4 are several thousand. R5-6 are several hundred.

I'm not sure about R1-2. These provide enough bias current to make the transistors hold their state. But that current must not be so great that it cannot be overcome by the toggle pulse.

The capacitors can be sufficiently large to slow down the action so our eyes can follow.

If you wish, you can replace the PNP's with NPN's, and reverse the diode directions, and reverse the supply polarity.

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rajaram04 said:

Sir which capacitor you are talking about ? C3-4 ?????

So would you tell any of approx value ??

are these of ceramic or electrolytic type ???

And what about C1-2 value ??

What about diode ? i mean IN4147 is okk for that ?

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one more circuit i found while googling . . Is it okk ? What should be the value of C1-2 ????????????

View attachment 90580

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BradtheRad said:

The answers depend on what speed you're operating at. Fast speeds go with small capacitor values, and fast recovery diodes.

If the capacitor charge is first positive, then negative...
then you cannot use an electrolytic.

Try what I do. Start at 1uF. Experiment with circuit operation, see how fast the capacitor charges and discharges. If it seems 'too slow', reduce the Farad value. Etc.



This is from the Navy Electricity and Electronics Training Series.
Module 9—Introduction to Wave-Generation and Wave-Shaping.
Page 117. Figure 3-17A.

www.hnsa.org/doc/neets/mod09.pdf

Although the text has an explanation, the schematic omits the toggle switching method.

To develop a working circuit, I made a simulation:



The capacitor values are chosen so they charge and discharge at what seems like a 'reasonable' rate.

Notice the transitions are not clean.

Operation is not always reliable. A toggle event needs to charge/discharge the capacitors, or else it puts the circuit in an unstable condition. As though it needs a moment to 'make up its mind' whether the left-hand transistor should conduct, or the right-hand.

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rajaram04 said:

hmm sir as per instruction i did but its not working like a bi-srable
when i make it trigger & hold the state changes & when i release the state returns back to original or previous condition :roll:

what to do now ?

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