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Increase In Output Pulse As Supply Increases In 555 Timer, Why?

vijaykrishna

Sep 9, 2017
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This circuit is constructed using 555 timer for 1sec on and off delay, output of 555 timer was connected to coin vibrating motor through transistor. But as power supply increases from 5v on and off delay increases. Any solution for this issue???
 

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(*steve*)

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What sort of capacitors are you using? Some can vary in capacitance with voltage.
 

(*steve*)

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Place a small capacitor across the motor and another one across the pins of the 555.

I suspect that noise from the motor is affecting the detection of the upper and/or lower thresholds. Changing the battery voltage may also change the impedance of your supply leading to more or less effect from the motor.
 

vijaykrishna

Sep 9, 2017
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Place a small capacitor across the motor and another one across the pins of the 555.

I suspect that noise from the motor is affecting the detection of the upper and/or lower thresholds. Changing the battery voltage may also change the impedance of your supply leading to more or less effect from the motor.

is it 2 capacitors or 1 capacitor connected to 555 and motor?
 

(*steve*)

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Two, one across the motor, one across the power supply pins of the 555
 

(*steve*)

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You probably want a 0.1uF 50V capacitor across the motor, and a 100uF across the 555.
 

vijaykrishna

Sep 9, 2017
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one more thing, output of 555 timer without coin vibrating motor is 3.5v for 5v supply. but when i connect motor it reduces to 2.5v and causes less vibration. can i know why and how to overcome? i even tried using amplifier. also i tried using arduino with code(blinking led), without motor it was 5v with motor it was 3.5v
 

(*steve*)

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That's because The 555 cannot supply infinite current nor swing from rail to rail. You could use the output of the 555 to switch another transistor to drive the motor. Also, you need to put a reverse biased diode across the motor.
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
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one more thing, output of 555 timer without coin vibrating motor is 3.5v for 5v supply. but when i connect motor it reduces to 2.5v and causes less vibration. can i know why and how to overcome? i even tried using amplifier. also i tried using arduino with code(blinking led), without motor it was 5v with motor it was 3.5v
I see a puny 9V battery in your video. With that in mind I don't understand any of this quote. o_O

Chris
 

CDRIVE

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Thanks for explaining that.

Chris
 
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