Need Hint/Direction For control of 12V via 8M

[powellite]

Hi;
I'm using the picaxe 8M to attempt control on/off of a microtransmitter which needs (12-13.8V) to operate through a 8 cell AA battery pack. I realize the 8M has less than 5V output on pin 2 which I've programmed to turn the transmitter on/off. Pin 2 high, wait xx, pin 2 low...etc... but obviously cannot initiate the correct 12V power output to the transmitter.

In a general sense, what's the best way to use the 8M to control a larger voltage in that 12-13.8V range? (insert helpful hint here).

My apologies for my limited electrical background. Just need a helpful hint to muddle through. Looked through the forum but can't find anything significant for my problem. A link or two would work too

thanks

Dan

 

[Taniwha]

depending on duty cycle I would look at driving a relay off the 08M, there is an overview in part 3 (i think?) of the manual that shows exactly this setup.

 

[BeanieBots]

Welcome to the forum.

Have a look at manual 3 page 5.
No need for a relay, just use a single transistor + resistor in series with base as shown in the diagram.

 

[BCJKiwi]

What current draw is there on the transmitter?
What duty cycle (as per Taniwha's query)?
Note the PICAXE port can only deliver a max of 20mA (preferably less) so if a relay is suitable for the duty cycle, care must be taken to ensure the coil does not have too high an in rush current at turn-on.

Any of the four options in Section 3 of the manual as described on pages 5,6,7 would be suitable provided the ratings stack up.

 

[powellite]

Thanks to all for pointing me in the right direction. I'll read the suggested manual/pages appropriate to my question.

FYI - the draw is 300mW (3-5 seconds on then 20 seconds off). This continues for about 6 hours, then sleeps for 18 hours then the cycle starts over again.

cheers
Dan

 

[BeanieBots]

That's only 25mA from a 12v source, so just about any old signal transistor will do the job.