remote wire, transistor = switch?
05-10-2009, 03:07 AM
#1
remote wire, transistor = switch?
Hi. So my question is, can I use a transistor to turn something on with a use of remote wire. The idea is if i turn my deck on, I want to turn something else on. The transistor is also used to amplify current, so i'm not sure if I will damage the device I want to turn on (a small fan that works at 12V dc) . My plan was to run remote wire to BASE, the Collector will be connected to the main power wire (12V) and EMITTER will be connected to the positive wire of the little fan. Now I guess the fan wont be using much current so I will need small transistor, but if i chose transistor to big can i fry the fan?? My understanding is that if voltage is constant then the current will be varying, so i don't have to worry about putting to many amps in that fan, but if transistor somehow will amplify that current then I guess i can be in trouble....
P.s> Is the principal the same as for bigger setups(with a higher Ic value of the transistor of course) ? (lights, electric motors etc?)
P.s> Is the principal the same as for bigger setups(with a higher Ic value of the transistor of course) ? (lights, electric motors etc?)
05-10-2009, 11:46 AM
#3
if you referring to a relay switch, its not really solving this problem.... if you mean solenoid relay- cant find one that's small enough, if SSR (solid state relay)- can't find them at all...
Last edited by LaZyLuke; 05-10-2009 at 11:46 AM. Reason: typo
05-10-2009, 12:18 PM
#4
500 Watt CAFz'r
Join Date: Sep 2008
Posts: 819
There's no danger for the fan if the power source is 12v also, a single transistor will not increase the voltage. For the amps, it will vary depending of the load, but will never exceed the limit of the transistor or the power source. A transistor is basically a diode that let you control the flow (with the base) that goes tru it.
Look on google i'm sure you will find tons of info and circuits like this Simply Transistors, also when you choose your transistor be sure that the load will not exceed the termal limit of the chip.
Look on google i'm sure you will find tons of info and circuits like this Simply Transistors, also when you choose your transistor be sure that the load will not exceed the termal limit of the chip.
05-10-2009, 09:31 PM
#6
There's no danger for the fan if the power source is 12v also, a single transistor will not increase the voltage. For the amps, it will vary depending of the load, but will never exceed the limit of the transistor or the power source. A transistor is basically a diode that let you control the flow (with the base) that goes tru it.
Look on google i'm sure you will find tons of info and circuits like this Simply Transistors, also when you choose your transistor be sure that the load will not exceed the termal limit of the chip.
Look on google i'm sure you will find tons of info and circuits like this Simply Transistors, also when you choose your transistor be sure that the load will not exceed the termal limit of the chip.
One more thing- the diagram you placed link for- ther eis only one 12V connection. If I want to use the remote wire as an indicating "switch" where should i place it?
Last edited by LaZyLuke; 05-10-2009 at 09:34 PM.
05-10-2009, 10:50 PM
#8
500 Watt CAFz'r
Join Date: Sep 2008
Posts: 819
{start disclaimer}I have only very basic knowledge about transistors, don't go full scale only based on my post... {/end disclaimer}
You should cut the link between the +12vcc and VR1 and use the remote 12v at the VR1. I guess you could remove the 2 resistors, but i would keep them to give you control on the fan speed. On more thing, like i said the transistor is like a diode so the 12v you apply at the collector will only come out as 11.3 (0.7v drop for silicon component).
You should cut the link between the +12vcc and VR1 and use the remote 12v at the VR1. I guess you could remove the 2 resistors, but i would keep them to give you control on the fan speed. On more thing, like i said the transistor is like a diode so the 12v you apply at the collector will only come out as 11.3 (0.7v drop for silicon component).
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