Triggering an external switch

[k_shirtcliffe]

OK, be patient with me here as I'm sure there is a simple explanation!

I have a seperate pre-made circuit (a toy voice recorder module) which is triggered by a push to make switch. I want to activate this circuit via infrared.

So far I have created the IR input stage using an 08M, the circuit is attached. This is simple enough, but now I am unsure how to trigger (or I suppose I mean short together) the switch which activates the voice recorder module.

Should I be using a relay, transistor or could I just have an 08M output pin going to one side of the switch and the other side of the switch running to the ground of the picaxe circuit?

I'm sure there is a basic electronics solution but my brain is fried!

Thanks in advance for your suggestions,
Kev

 

[Dippy]

Got a multimeter?

Switch on your voice recorder device
Measure voltage each side of switch wrt ground.
Also note the polarity.

Set your multimeter to 100mA range.
Put the probes across switch contacts - this is like pressing/shorting the switch except now you will be measuring the current going through switch. (i.e. your ammeter will be shorting the switch).
If there appears to be no current but you have trggered the recorder then do it again at a lower mA setting.

Switch off the Voice recorder.
Set multimeter to Ohms/Resistance.
Measure each side of switch with respect to ground.

Most electronic devices are logic switching to Ground or V+. (Not all so don't start an argument )
If one side of switch is ground it will show mV when powered up and a few ohms when powered off.
If the current is just a few microamps/milliamps it is possible to trigger directly from PICAXE maybe via a 100R (One hundred Ohms) resistor or less.
If you want to play safe (recommended for newbies) then do switching via an NPN transistor.

Do you know how to use an NPN as a simple switch? No? Then look in the manual 3 under "standard circuits - the transistor". But don't just look, please read and absorb.

If the readings are something else then we can look again. But yes, a transistor/relay would do it - again look in Manual 3 how to connect a relay.
Relays easiest, but it should be perfectly easy with a transistor.

 

[moxhamj]

If you have no knowledge at all about the sound recorder, use a relay. Reed relays are small and use little current.

If you can look at the tracks etc and work out the sound recorder circuit, and it seems to short a pin to ground, there might be a more cunning circuit. If a pin is shorted to ground, connect that pin to a picaxe IO pin, eg pin 1 or 2. To turn the switch on, set that pin to Low. To turn the device "off", make the picaxe pin a high impedence input, eg execute a readadc in code or any other instruction that makes a pin an input.