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I am trying to build a bistable multivibrator using NE555 timer. The datasheet says the operating voltage should be in the range 4.5V-17V, but during testing I have observed that my circuit works even when I provide a supply voltage of 3.3V. The problem I have encountered is that as I change the operating voltage (3.3V, 4V, 5V etc.) the frequency of my output signal keeps varying.

How do I know which is the optimal/accurate supply voltage to ensure that I obtain the correct frequencies?

The output frequency of the square wave is what I need for my testing.

JRE
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Rohit Kumar
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    "frequency keeps varying" ... if you need an accurate and stable frequency, a 555 is probably the wrong tool for the job. –  Mar 14 '20 at 11:52
  • I dont have the option of changing the 555 , wanted to know which is the best range of operating it between 3.3-7V – Rohit Kumar Mar 14 '20 at 12:00
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    Above 5v, and regulated. –  Mar 14 '20 at 12:16
  • This is a canned comment to let you know that it looks like you're trying to implement something that is non-trivial with the power-hungry NE555 but is very easy for someone using a microcontroller. – Marcus Müller Mar 14 '20 at 12:25
  • What do you mean by the "frequency" of the circuit in **bistable** mode? Can you share a timing diagram to illustrate what you mean? – The Photon Mar 14 '20 at 16:01

1 Answers1

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There is normal manufacturing variation in components, including the particular 555 integrated circuit you have in your circuit. You have not even told us the exact part number or manufacturer of your device, much less provided a link to the datasheet.

So, if you want to know the optimal supply voltage there is only one way to find it: do the testing yourself.

If you wanted a good enough result, and if you could quantify what "good enough" meant to you, then it might be possible to apply engineering expertise and judgement to help you.

Elliot Alderson
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  • Hey Elliot, it just appeared to me that we might want to have a "reference question (and answer)" that we can just refer this kind of askers to: "I've noticed the NE555 isn't appropriate for my application or makes it much harder, so is there a simple replacement for these common types of NE555 applications: {list of the typical things}" with a wiki answer, where we'd refer people to simple other one-off triggers, ramp generators, PWM generators…; would you be in for that? – Marcus Müller Mar 14 '20 at 12:45
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    @MarcusMüller I think that is a great idea. I would defer to someone with more 555 experience to start drafting that response. My main concern is trying to get beginners to write good, actionable questions. – Elliot Alderson Mar 14 '20 at 13:06
  • I have mentioned that i am using NE555. It is manufactured by Texas Instruments.the link to the datasheet is http://www.ti.com/lit/gpn/ne555 i have done the testing myself already for different ranges just not sure what are the correct values because i dont have a reference. – Rohit Kumar Mar 14 '20 at 13:56
  • Q&A is live, @ElliotAlderson: https://electronics.stackexchange.com/questions/486156/replacements-for-ne555-circuits-or-why-and-how-should-i-replace-my-ne555/486157#486157 – Marcus Müller Mar 14 '20 at 14:49
  • @RohitKumar still a bad case of "nah, the 555 isn't what you need here" – Marcus Müller Mar 14 '20 at 14:50
  • @RohitKumar According to Octopart, the "NE555" is made by Diodes Inc, STMicroelectronics, ON Semiconductor, NXP Semiconductors, Microsemi, and Texas Instruments. This is one of the most ubiquitous part numbers and there is no reason to assume that parts from different manufacturers have identical behavior, even if their spec limits are the same. What do you mean by "a reference"? A reference document? A voltage reference? – Elliot Alderson Mar 14 '20 at 16:05