Author Topic: Dual 555 Timer (with inverted signal) for H Bridge Problem  (Read 2335 times)

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Offline z7d8tsgTopic starter

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Dual 555 Timer (with inverted signal) for H Bridge Problem

I tried this circuit but it doesn't work. Any thoughts?

Thanks,

- Dan

 

Offline David Cutcher CEG

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Re: Dual 555 Timer (with inverted signal) for H Bridge Problem
« Reply #1 on: May 15, 2019, 11:49:12 pm »
You say "H Bridge problem." 
You need to be more specific.
What is the problem? 
Is this a problem for school?
What is the expected output?
Not enough information here for me to attempt a helpful answer.

David Cutcher "Certified Evil Genius"
 

Offline z7d8tsgTopic starter

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Re: Dual 555 Timer (with inverted signal) for H Bridge Problem
« Reply #2 on: May 16, 2019, 12:22:20 am »
im building an h bridge that uses 2x 555 timer with optocoupler non zero gate crossing (k3011p). It needs to run off of 1x power supply at the end, I will be using voltage regulators to regulate voltage and resistors to split amperes properly. Is for a high accuracy remote car

Best,
- Dan
 

Offline David Cutcher CEG

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Re: Dual 555 Timer (with inverted signal) for H Bridge Problem
« Reply #3 on: May 16, 2019, 05:12:49 am »
The original circuit, attached, should work. I'm uncertain about where your added lines are connected.
Also, as noted on the circuit, this is using a split voltage. You don't indicate that on yours.
David Cutcher "Certified Evil Genius"
 

Offline soldar

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Re: Dual 555 Timer (with inverted signal) for H Bridge Problem
« Reply #4 on: May 16, 2019, 07:50:40 am »
That circuit could have some serious shoot-through problems.
All my posts are made with 100% recycled electrons and bare traces of grey matter.
 

Online Zero999

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Re: Dual 555 Timer (with inverted signal) for H Bridge Problem
« Reply #5 on: May 16, 2019, 09:38:22 am »
The original circuit, attached, should work. I'm uncertain about where your added lines are connected.
Also, as noted on the circuit, this is using a split voltage. You don't indicate that on yours.
David Cutcher "Certified Evil Genius"
That will work, but not very well. There will be a huge voltage drop of about 6V, given a current draw of a couple of Amps, because of the Darlington pair configuration and the 555's output stage drops over a Volt, on the high side.
 

Offline z7d8tsgTopic starter

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Re: Dual 555 Timer (with inverted signal) for H Bridge Problem
« Reply #6 on: May 16, 2019, 01:00:10 pm »
How can I make a potentiometer change the frequency while keeping the duty cycles at 50% for both pwm signals?
 

Offline malagas_on_fire

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Re: Dual 555 Timer (with inverted signal) for H Bridge Problem
« Reply #7 on: May 16, 2019, 01:11:52 pm »
Another space improved idea is using a 556 which consists a chip with two 555 timers sharing the same power source :P.  Drive the mosfets with some transistors between the 555's and the Gate's, "doodle" something for "H bridge DC motor. ".

PS: I'm making an assumpcion on driving improperly the H bridge , but more data would be good to assist .
« Last Edit: May 16, 2019, 01:20:59 pm by malagas_on_fire »
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Online Zero999

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Re: Dual 555 Timer (with inverted signal) for H Bridge Problem
« Reply #8 on: May 16, 2019, 01:44:33 pm »
How can I make a potentiometer change the frequency while keeping the duty cycles at 50% for both pwm signals?
The classic is to use the 7555, instead of the normal 555.


A 555 timer isn't the best circuit to use to get 50% duty cycle. I've built the above circuit and it didn't give a perfect 50% duty cycle output. It's better to use an oscillator and divide by two counter. The CD/HEF4013 work quite well.



 


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