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Need a little help and understanding of a 555 timer circuit.

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coryjones

New Member
Here is what i am trying to do i want to turn a dc pump on and off faster then 1 second intervals. Basically this is being used to create waves in a reef tank. I have found people doing this with three wire tunze pumps but i have a 2 wire resun. I have built 2 types and they have both failed. I don't know if it is because the pump draws 1.5 amps and is 24 v dc.

Is there a good article or better yet a video on how the 555 timers work? I see people making leds flash with them so i should be able to get this pump to turn on and of right? The first one i built was this but could not get it to work i am not sure where my positive and negitive in and out go.



I use to play more with electronics back in high school and would like to get back in to them and get my son in to them as well.
 

tcmtech

Banned
Most Helpful Member
I doubt your pump motor will actauly be able to speed up and slow down in one second or less. Plus that much start and stop cycling will could kill the motor too!


For short waves a simple mechanical motorized bobber would probibly do much better.
 

coryjones

New Member
These guys are saying that they work fin long term it is not speeding up and down it is turning off and on.
 

coryjones

New Member
It would take a larg bobber to make 90 gallons swell but if you have any ideas i am open to them.

I doubt your pump motor will actauly be able to speed up and slow down in one second or less. Plus that much start and stop cycling will could kill the motor too!


For short waves a simple mechanical motorized bobber would probibly do much better.
 

k7elp60

Active Member
With the diagram you posted Pin 1, is the output,Pin 2 is the - supply, and Pin 3 is the + supply. Most 555's have a maximum supply voltage of 18V. The 555 will not drive the motor directly, but it will drive a power mosfet to turn the motor on and off.
 
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coryjones

New Member
Ok I looked up power mosfet and it looks to me to be kinda a relay that can come on and off quickly. Is this right? anyone willing to help me design a circuit to get this to work? I would really appreciate it and my Corals would too. I want to make this work there is a lot of people out there that would like to figure out how to build this.
 

coryjones

New Member
I am not sure what you mean there is no pin 3 there is 1 2 and 5 So what is the output + or -? I would assume it is positive with the cap going across it right? This pump will run at 12v and the power supply is adjustable so maybe i will rebuild it and try it at 12v for starters.

With the diagram you posted Pin is the output,Pin 2 is the - supply, and Pin 3 is the + supply. Most 555's have a maximum supply voltage of 18V. The 555 will not drive the motor directly, but it will drive a power mosfet to turn the motor on and off.
 
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smanches

New Member
It's not just suggested, but needed. The amount of current a motor draws is magnitudes greater than what the chip can supply. You need the mosfet to act as a high power switch that is controlled by the 555 IC.
 

k7elp60

Active Member
So what one would you suggest and how would i add it?
Please see my original post for some corrections.
I would recommend and IRFZ44 n channel mosfet, and suggested circuit is posted.
 

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colin55

Well-Known Member
Now draw a 555 as a schematic - not as a "layout" above - so you can see how the chip is operating, and add the MOSFET and motor section (as shown above).
I can then comment on your circuit.

<mod edit: self promotion deleted. If you have content to share, please post directly to ETO. Do not link to your own personal website.>
 
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coryjones

New Member
This is a diffrent type of pump i do have the contrller for this one but i don't think it will be of much use. It changes speeds every few seconds by changing the voltage.
 

colin55

Well-Known Member
You have to be more specific. We have absolutley no idea what you are talking about.

It's a bit like:
They have this thing. They clip it onto my wrists when I do soldering.

Who would know I am in prision and when I work in the laboratory, they hand-cuff me?
 
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coryjones

New Member
Here is what i want it to do. I have a 24v dc pump i want it to turn of and on very quickly. From 1 second to steady on. It draws 1.5 amp max the circuit that i listed is for a dc pump but it is setup for a controller that comes with it. I dont know what is in the controller and dont care. I am just trying to build a curciut to turn this pump i have on and off quickly. I am not sure what else you want to know.
 
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