controling a device on a 12V circuit

[christree]

I would like to switch on/off a 12 volt ciruit that controls a water pump. How can I interface this 12v circuit with my do picaxe08 5v circuit to control the waterpump?

Thanks,
Chris

[Michael 2727]

Is the entire circuit 12V or is that just the control voltage for the pump,,?
What determines the switching at present,,?

[Rickharris]

Easy answer use a 5 volt relay - harder answer use a suitable transistor or MOSFET or Darlington driver. There is some information in the manuals.

[Michael 2727]

Picaxe_manual3.pdf/page7/standard circuits 4.
shows how use a MOSFET.
The post a couple back may give you an idea on how to get a 5V input from 12V supply -
Protecting analog inputs.
Or if 12V is only the control voltage for a 240V pump you can use a SSR (Solid State Relay) via a 330 Ohm resistor from any
picaxe output to directly drive it.
For a 10A motor, suggest zero crossing/switching
SSR only and rated at 40A or more to cater
for heavy start currents.

[christree]

The 12v circuit is a 12v power supply simply hooked up to a 12v water pump. I would like to switch it on/off with the picaxe. I'll look in the manual which you mentioned. Do you know of any circuit diagrams that may help? I'm new at electonics so I'm not sure what the MOSFET is, and how to connect the relay at this momment.
Thanks,
Chris

??

[andypro]

I know IGBT's arent in the manual, but may I suggest them as a switching alternative?

There are IGBT's (Insualted Gate Bipolar Transistors) that can be switched with logic levels, a suitable resistor on the picaxe is all that's required to turn them full on, and they can handle massive anmounts of power (relatively).

--Andy P