Circuit Astable

Discussion in 'General Electronics Chat' started by cheshmayebaruni, Dec 28, 2012.

1. cheshmayebaruni Thread Starter New Member

Dec 28, 2012
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Hi I Astabl Op Amp circuit (without chip 555) with a 50% duty variable frequency between 1K to 10k want - Dvstal please help me

2. ScottWang Moderator

Aug 23, 2012
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You may use google to search - op amp astable multivibrator.

Sep 20, 2005
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4. WBahn Moderator

Mar 31, 2012
23,866
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I can't make heads or tails of what it is you have versus what it is you want. I'm pretty sure there are some English-as-non-native-language issues here, but we can work through those. So please reask your question, being a lot more specific as to what you are trying to find out. Keep in mind that we are probably going to struggle with your English and if we can piece together information from different parts of your post it will make that a lot more doable; it is basically an error correcting code -- we need quite a bit of redundancy to work around the language obstacles.

5. cheshmayebaruni Thread Starter New Member

Dec 28, 2012
22
0
am sorry...

Circuit Astabl Design with :

Output frequency Between 1 Khz > F > 10 Khz

Duty Cycle : 50%

Opamp Supply : +15 & -15

Output Voltage wave Pulse : between : 5v > V out > 10v

6. WBahn Moderator

Mar 31, 2012
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7,384
What have you tried so far?

Is this a school assignment of some kind?

7. Brownout Well-Known Member

Jan 10, 2012
2,364
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The simplest circuit uses a resistor connect from the output to the "-" input, and a capacitor from the "-" input to ground. The capacitor charges/discharges from the opamp's output, and causes the state to switch. In this scheme, you need a resistive network from the output to the "+" input for hysterisis. That provides a deterministice "switch point" for the amplifier. Please consult the internet for circuit details. There is too much information available for this circuit for me to try to produce it here.

Mar 24, 2008
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9. absf AAC Fanatic!

Dec 29, 2010
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You're not allowed to use 555... Is that correct? Only op-amps are allowed?

Allen

10. WBahn Moderator

Mar 31, 2012
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If you look at the internal block diagram for a 555 timer IC and then figure out what parts you can remove and/or simplify under the condition that you want a free-running ASM, I think you can reduce it to pretty simple op-amp circuit (but I'm just going off the cuff, so I might be wrong and you need something else, but I think that would be a good place to start.

On a more general note, when told to do something without using X, one of the first things to consider is why is X being excluded? What is it about X that would make the task easier and can you get that same behavior another way.

11. cheshmayebaruni Thread Starter New Member

Dec 28, 2012
22
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I have not to use 555.

only Opamp

i have Circuit Original form

12. WBahn Moderator

Mar 31, 2012
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7,384
I'm not saying to use a 555. I'm saying to look at the internal block diagram for guidance on how you can implement that part of the 555's functionality that is applicable to your project.

cheshmayebaruni likes this.

Dec 28, 2012
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