zero88 frog remote switch

[matt freeman]

for those of you who use a frog desk, its got a 8pin DIN connector which you can plug up to 6 remote switches into.

to trigger the switch you have to short the switch pin, to the ground pin.

now, if I want to make a remote switch, all I have to do is stick a push to make switch across these pins, however id like to have an LED which lights when the switch is pressed, so you know uve done it.

I very much dout there is enough pwoer from the desk to do this, so ill have to add a battery into the circuit.

but would this added current damage the desk, or stop the remote switch from working?

 

and ideas greatly received.

 

thanks

matt

[cutlunch]

The simplest way to do this would be to use a double pole switch. In a double pole switch both sets of switch contacts are activated at the same time but are electrically independent. Then all you do is wire the desk to one set and the battery- LED to the other set and then you don't have to worry about the current.

 

Hope this helps.

[Freddie]

If you ask over on the Zero88 Forum, someone will be able to tell you for sure whether the desk can give enough power. Agree on the double pole switch thing. You'd wire it up thus: http://img.photobucket.com/albums/v316/rightguardextreme/th_frog.jpg (Click to enlarge)

[Tomo]

What you are actually doing is pulling the voltage of the output from it's normal level (probably 5v) down to 0v, which means that an LED might stop it seeing the switch close.

It wouldn't damage the Frog as the path resistance would increase, reducing the current expected to flow through the switch.

 

So basically, feel free to try it but one of three things will happen:

1) LED doesn't light, Frog may or may not see the switch close (can't supply enough current through internal bias resistor)

2) LED lights, Frog doesn't see switch close (not enough voltage drop)

3) Everything works.

 

I'd expect 1 or 2, but without a Frog or a schematic of that section I can't say for certain.

 

The double-pole system suggested by cutlunch and Freddie would definately work, and the cost would be minimal. Go for that!

Also, 12Vdc 0.4A is available on the desklight connector between pins 2 and 3 - stick a passthrough to the desklight, drive the LEDs from that.

Take care to ensure your desklight is low enough power though - all six LEDs lit at once will draw ~0.18A.

[matt freeman]

thanks for that,

I did ask zero88 support, and they replied with the douple pole switch idea.

 

ive ordered the componants ill need off rapid this morning, so once they turn up, and I get back to school from half term to try it on the desk, ill stick a post on with the end result.

 

could take a while, im having an attack of GCSE's at the moment, but thats only another 3 weeks.

 

matt