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Does a lithium polymer battery have too much amperage for a 555 timer? Answered

I'm using a 555 timer for a robot, and i was wondering, is a lithium polymer battery too much amperage for the 555 timer? because when i use it, the 555 timer warms up, to a point where i cannot touch it without getting burned instantly. If so, how can i reduce the amperage, so that it can be used with the 555 timer?
I'm using a 7.4 volt, 1000mAh battery, it was originally used for a helicopter, but i re purposed it for my robot...

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AndyGadgetBest Answer (author)2010-05-12

The 555 itself will only take the current it needs from the battery, and this will be very low.
However, any load you connect to the 555 output will also pass through the chip and this is what is heating it up.  If the question relates to THIS project, you say you are using Tamiys FA-130 motors.  From the DATASHEET for that motor, there's 3 variants, two of which are rated for 3V, the other up to 4.5V, so you're already overdriving the motors and the current they draw will be higher.  The slowest motor gives an off-load current of 200mA which is the maximum the 555 can safely source or sink and this will rise under any load.
Basically, you're expecting too much of the 555 and the motors.  You will need a more sophisticated circuit to drive adequate current to the motors and reduce the voltage to prevent them burning out.


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steveastrouk (author)AndyGadget2010-05-12

Pretty well what I prophesied in that last question ChowMix. Andy's saying what I said at the weekend - too much current from the 555.  

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Chowmix12 (author)steveastrouk2010-05-12

i replaced the li-po and started using 4 AA batteries and it worked out a lot better. what does that mean then?

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steveastrouk (author)Chowmix122010-05-12

You had 7.4V, you now have 6V, all things being equal, that means its now taking 35% less power.

Steve

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Chowmix12 (author)steveastrouk2010-05-25

Here are some pics of the finished product...

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Chowmix12 (author)steveastrouk2010-05-12

but now it works... i think it is a little bit over the 200mA mark aat worst conditions ( 10mA) over. Thank you all!!

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Chowmix12 (author)Chowmix122010-05-13

is there  any replacement to the LDRs? or is there anyway to improve it to 360deg light sensing? i was thinking a diffuser...

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Re-design (author)2010-05-11

Maybe it's the voltage is too high or whatever you are powering with the timer is drawing too much current.

You could power the timer using a one million mah battery and as long as the voltage was right and the load was not too much it would not hurt the timer.

But if you can't hold your finger on the chip then I agree it's too hot.

And- be careful charging and using that lith battery.  Go to youtube.com and search lithium fire to see why.

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Chowmix12 (author)Re-design2010-05-11

the warmth is instantly noticeable.. i think i may try a different power source.

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Re-design (author)Chowmix122010-05-11

What are you driving with the timer?

It's the load that is causing the heat.

Can you show us the diagram or a photo?

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Chowmix12 (author)Re-design2010-05-12

this is the diagram I'm using, to make a light seeking robot!

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Re-design (author)Chowmix122010-05-12

Well there's your problem.  I don't think the 555 can pass that much current to run the motors without over heating.  You should be running them off a relay or electronic switch controlled by the timer.  That way the timer only controls a very small load instead of a large one.

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Chowmix12 (author)Re-design2010-05-11

also, i believe the max voltage is 14 volts. i dont think its to high of a voltage output.

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XOIIO (author)2010-05-11

"Is a lithium polymer battery have too much amerage..."

We have autocorrect for a reason.

You could just google the amperage of a 555 timer.

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Chowmix12 (author)XOIIO2010-05-11

but i dont know the amperage put out by the lithium polymer battery...

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Re-design (author)Chowmix122010-05-12

You're not reading this.

It doesn't matter how much current the battery can supply.

What matters is how much current the load is using. 

What are you running with your timer?  What ever it is, it is probably using too much current.

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Chowmix12 (author)Re-design2010-05-12

I have two motors in series that is hooked up in parallel with the 555 timer.

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steveastrouk (author)Chowmix122010-05-12

A battery can supply a maximum current, limited by its internal resistance, to what are termed "short circuit amps", it is often in the 10s, and maybe in the many thousands of amp level. Your circuit draws a current from the battery that supports the apparent resistance it offers to the battery, the battery doesn't force a current on your circuit, it provides a voltage.

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rickharris (author)2010-05-11

An electronic circuit will draw the current it needs.

TOO MUCH available isn't a problem - too little may be a problem.

The law which connects current, voltage and resistance is ohms law.

SO if you 555 is getting hot then you are drawing too much currentfrom the 555.

Because the LIPO can provide a large current this results in your 555 getting hot as it tries to supply the demanded current.

Check your circuits and the current capabilities of the 555 timer. according to this  data sheet you should draw more than 200mA max from the 555 at 15 volts supply.

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