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Electronics => Electronics => Topic started by: Stephanie on August 20, 2009, 10:52:43 AM

Title: [Solved] Sharp IR capacitors
Post by: Stephanie on August 20, 2009, 10:52:43 AM
I want to purchase some 10uF electrolytic capacitors to put between power and ground of my sharp IR rangefinders. I don't think I'll find ceramic around here.

But what voltage?
Title: Re: Sharp IR capacitors
Post by: Canabots on August 20, 2009, 11:10:26 AM
well, the power requirements for the sensor is 5VDC. So assuming that that's the voltage you'll be supplying to the sensor, any capacitor rated at 5V or higher should suffice. Though higher shoujld be better, just to lower the risk of the capacitor blowing  :P
Title: Re: Sharp IR capacitors
Post by: Stephanie on August 20, 2009, 11:12:49 AM
Is 100v ok? hehe
Title: Re: Sharp IR capacitors
Post by: Canabots on August 20, 2009, 11:19:08 AM
It should be fine. Remeber the rated voltage is the the max it can handle.
Title: Re: Sharp IR capacitors
Post by: sonictj on August 20, 2009, 11:38:51 AM
Quote
any capacitor rated at 5V or higher should suffice

This is true except most caps have a +-20% tolerance this would mean the max voltage could be as low as 4V or as high as 6V.  Its best to use a cap rated a little higher than the voltage of your circuit.
Title: Re: Sharp IR capacitors
Post by: Stephanie on August 21, 2009, 04:12:12 PM
Okay.

I purchased some 63V 22uF electrolytic capacitors from a local store.

Now, how do I install them between GND and Vcc?

This is how I think it is (look at the image):

(http://img13.imageshack.us/img13/9820/guesssdq.jpg)

- Cut and strip the Sharp IR + and - wires.
- Solder the longer leg of the capacitor to + and the shorter leg to -.

But I was afraid to try because there'll be three ends in each of the cuts: the two parts of the wire and the capacitor leg. Is that correct?

Also, any tips or things I should know about?

edit: typo
Title: Re: Sharp IR capacitors
Post by: Canabots on August 21, 2009, 04:39:34 PM
Instead of cutting the wire, why not just push the leads in either the JST or Molexx header? I have to use a resistor on my GP2D15, but I didn't modify the cable.

Also, like LEDs, the length of the legs isn't exactly how to determine the polarity of the capacitor. You see the thick band down one end of the cap? That's your negative, you connect that to GND. The other end goes to Vcc.
Title: Re: Sharp IR capacitors
Post by: SmAsH on August 21, 2009, 04:53:40 PM
i agree with canabots about not touching the wires.
you could try soldering it to the other wise of the header on the actual sharp ir?
i try to never judge polarity by leg length because what if someones trimmed the legs?
Title: Re: Sharp IR capacitors
Post by: Stephanie on August 21, 2009, 06:59:58 PM
Thank you all!

It worked great. I put the capacitors inside the JST connectors, and trimmed the leads so they won't escape. Now I can finally use my Axon with Sharp IRs!  :D