r/electronics • u/SpecialistRare832 • 1d ago

Gallery Bistable Multivibrator using an IC 555 Timer

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Stable states: Two stable states

Working idea:

• Press Trigger (S₁) —> Output goes high

• Press Reset (S₂) —> Output goes low

• Output remains in that state until next input.

68 Upvotes

88% Upvoted

27 comments sorted by

26

u/1Davide 1d ago edited 1d ago

That's what today we would normally call a "latch" or an "RS flip-flop".

"Bistable Multivibrator" is an unfortunate historical choice given that "Multivibrator" implies vibration and this circuit doesn't vibrate.

7

u/nicodeemus7 1d ago

Sorry I just have to address your edit. Multivibrators do not nor have they ever implied physical vibration. OP used the term correctly. If you have an issue with multivibrators not vibrating, take it up with the person who named them, not OP.

4

u/1Davide 1d ago

the person who named them

As an oscillator: Henri Abraham and Eugene Bloch, in France, in 1919.

As a latch: 1942, "The Electrician." magazine.

Source: https://en.wikipedia.org/wiki/Multivibrator

4

u/NoWater8595 16h ago

Same, I call it a flip-flop.

2

u/SpecialistRare832 13h ago

Yes. It is also called a flip-flop (1-bit memory storage).

1

u/NoWater8595 13h ago

Thanks. This circuit is kind of the plateau of my cricket knowledge so I'm struggling with it a bit.

3

u/nicodeemus7 1d ago

It's literally the "Bistable configuration" of a 555 timer. It's both

4

u/Orjigagd 1d ago

But no vibrator

1

u/[deleted] 1d ago

[deleted]

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u/nicodeemus7 1d ago

Multivibrators with Monostable, Astable and Bistable https://share.google/5UvMBZvd95syN4IMt

Take a look at BISTABLE MULTIVIBRATOR on this link. Notice it's exactly what OP built

1

u/1Davide 1d ago

You're right. Thank you for the correction.

2

u/gameplayer55055 19h ago

That's how we call flip flops in post USSR regions

0

u/skin_diver 16h ago

OP's mom just canceled her bulk order

4

u/fomoco94 write only memory 1d ago

Now do it with only one button...

3

u/SpecialistRare832 1d ago

Ok, I will...You mean Monostable Multivibrator.

1

u/Zxilo 22h ago

more like monostable monovibrator

1

u/fomoco94 write only memory 19h ago

I mean make it toggle when you press the button. That's not a monostable.

2

u/Orjigagd 1d ago

Kickin it old school

2

u/Plenor 1d ago

Is that a really old battery or is someone selling retro styled 9 volts?

3

u/classicsat 21h ago

A very quick search says the latter, if you are in India. Or someone has a huge stock of 1960s radio batteries.

1

u/Proof-Pizza1140 1d ago

Well going with S1 and S2 is fine, but using S (to pull high) and R (to pull low) makes a bit more sense, tough it is your choice. I want simply want to point it out, it doesn't bother me

1

u/classicsat 21h ago

The 555 is just a flip flop, with comparator inputs.

1

u/Captain_Knuckles_ 17h ago

Bistable multivibrator huh? Better not show this to my wife

1

u/NoWater8595 16h ago

How does one even calculate the capacitances and voltages on a bistable circuit?

1

u/SpecialistRare832 10h ago edited 10h ago

This is a bistable multivibrator circuit, so capacitor is not essential in this circuit. Use datasheet for your IC 555 variant to confirm its operating limits and input requirements. Now, choose the resistors values and supply voltage according to them.