Author Topic: Relays  (Read 1725 times)

Offline TW1NKY

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Relays
« on: August 02, 2008, 07:56:38 PM »
Does anyone know where to buy a relay that is normally ON but when there is voltage it opens the circuit? I tried radio shack and they didn't have anything, and I'm not sure what the part is called so I can't find it on Mouser. :dntknw:

Any help is appreciated  :hifive:


Offline Timmy

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Re: Relays
« Reply #1 on: August 02, 2008, 08:01:33 PM »
What you want is a Transistor

Heres a bit of FYI and Transistors 101

Basically a transistor has three Pins, a BASE, COLLECTOR and EMITTER

The main type used in basic electronics are Bipolar which come in NPN and PNP varieties

NPN



PNP



Whats the difference? Well In all bipolar transistors the Collector and Emitter pins act like a polarised switch, you put where your signal (for example power for an led) is coming from on the collector and where its going to on the emitter (the led +). The difference is what happens when voltage hits the Base pin, to explain this, think of the transistor as a water dam, theres a gate inside that lets a certain amount of water (signal) through depending on the pressure (voltage)   hitting the base pin.

In NPN transistors, the gate is "Open" , letting water through when there is high pressure on the Base, in PNP its when LOW pressure is hitting it

Easy way to remember this is "not pointing in" for NPN as it is not holding the signal in when power hits the base. And PNP is "points in proudly" as in it does retain when the voltage hits the base.

So you basically want a PNP transistor because you want it to close off when high voltage hits it and open when low voltage hits it.

Im not sure what you want to do exactly but say you want led's to turn off when you turn your console on (sounds stupid but for the examples sake bear with it) you have to find a point that switches between 0v when the console is off and 3.3-5v when on. You solder this to your Base pin, then you solder a different supply (say you draw off a PSP's power led to run parallel like in the trigger mod) to your collector pin and then solder your led's positive legs to your Emitter pin.

You can buy normal sized ones and smt ones from ebay, mouser and local electronic stores, if you tell me what your doing i can help you find a specific one
« Last Edit: August 02, 2008, 08:22:10 PM by TimmyDX »

Offline TW1NKY

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Re: Relays
« Reply #2 on: August 02, 2008, 08:41:26 PM »
Thanks, Timmy
the transistor would be for my pulsevu ds mod where the charger would put voltage through the transistor and turn the voltage to the pulsevu to 0v so it pulses while it is charging, similar to anthonyta's white psp slim


Offline Timmy

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Re: Relays
« Reply #3 on: August 03, 2008, 05:32:48 AM »
Hey thats a neat idea there man

basically all you'd have to do is connect the VIN point on the charger (its on the front side of the mobo below the gold connector) to your Base pin, the collector to where you'd usually solder your PO point on the PulseVU 2 (the one below works nicely) and your PO point to the emitter :D


Offline TW1NKY

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Re: Relays
« Reply #4 on: August 07, 2008, 05:54:10 PM »
Do you know how many volts come from the VIN point? I'm planning on using it to power the pulsevu when the ds is off


 

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