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schematic

simulate this circuit – Schematic created using CircuitLab

I have two 555 timers hooked up and I want them their duty cycle to be controlled by the same potentiometer.

The second one has twice capacitance on pin 2 so I want to be able to get the second one exactly twice slower than the first one.

If you need clarifications just let me know and I'll try to do my best to help you understand my situation.

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    \$\begingroup\$ Create a control voltage with a transistor and one potentiometer, feed this signal to two op-amps configured as buffers... Another option is to use a stereo potentiometer \$\endgroup\$
    – John Am
    Commented Nov 18, 2019 at 23:51
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    \$\begingroup\$ If you're designing a precision spec using a capacitor, you won't be happy with the outcome \$\endgroup\$ Commented Nov 18, 2019 at 23:58
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    \$\begingroup\$ If you want the 2nd duty cycle to be double the first, just use a divide by 2 and not a 555. \$\endgroup\$ Commented Nov 19, 2019 at 0:00
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    \$\begingroup\$ Not sure where all these commenters are coming from. You can't buffer a control voltage, because that isn't how the 555 is using the potentiometer -- the voltage across it varies throughout the cycle. And you can't use a DFF, because that would require the first 555 to pulse twice -- and the the output of the DFF would be the 555's period, not twice its pulse width. People, please THINK before commenting off-the-cuff! \$\endgroup\$
    – Dave Tweed
    Commented Nov 19, 2019 at 0:20
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    \$\begingroup\$ This is not a task for a 555. While it sounds excessive, in reality your most economical solution is likely going to be a low end MCU reading the potentiometer via an ADC - especially as you have not even defined the goal to the point where it can be implemented, but only hinted at aspects which are challenging for simple circuitry but easy for software. \$\endgroup\$ Commented Nov 19, 2019 at 4:16

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Just configure the 2nd 555 as a frequency divider f/2, and feed it with the first. Thats a basic circuit shown in almost every 555 timer book (eg Forest M. Mimms Engineers Mini-notebook)

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    \$\begingroup\$ Using a frequency divider does not allow you to control the duty cycle of the second output...the duty cycle will be 50%. \$\endgroup\$ Commented Dec 15, 2019 at 20:37

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