Accessories - do they need a .........?

All,

I'm thinking of making my bot a cop-bot

I've made up some flashing blue and red LED's to run on 12v, along with a siren ;-) I'm looking to use a servo to flick a switch to turn the lights/siren on and off.

As they run on 12v and my drive and weapon run on 18.5v I'm going to run a seperate circuit with a 12v battery, however will these need a removable link? They are not dangerous in anyway and they will be dead with the servo/switch and when the Tx is turned off with the digital failsafe.

Also can anyone suggest a good switch that a servo can flick on and off for a 12v circuit?

ta
billy

you could just use a remote controlled switch such as a battleswitch or a turnigy one:

http://www.ebay.co.uk/itm/RC-Turnigy-Re ... 1129wt_907

They really should have a removeable link as if there is a short there is no way to break the circuit, hot batteries are never good! The way around it would be to put a small relay into the circuit. Have the coil side paralleled up to the main power circuit (ie link goes in and it is activated) with the light circuit on the load side.

jonny thanks for the switch link that would be better.

good you suggest a relay for this idea?

thanks
billy

Something like this I would imagine;

http://www.ebay.co.uk/itm/SOLDERLESS-RC ... 1c1cf5d4d8

as a relay?

To operate a switch from radio gear you need 2 things. The switch itself (relay) that can handle the current of the circuit your powering, and something to turn that switch (relay) on and off via radio gear.

What I linked you to is both of those things in a compact unit (I believe). Never had a need to turn lights on and off!

that link is a rc switch like the one i gave you the link for. i think gary's saying that you could have a relay so that when you put the main robot link in power goes to the relay turning lights etc on, when link is removed no more power goes to relay and lights etc are turned off.

Oh I see, so you could have them on a different power source.

I think any Transistor, MOSFET or relay will do that, providing the lights don't draw a huge current.

I think you can get MOSFET's from the trigger assembly on cordless drills.

mosfets would be a bit trickier as you have to match up the right voltages. Just use a car relay like this one,

http://www.ebay.co.uk/itm/PCB-Automotiv ... 2eb6b17cbd

Over rated but will happily do the job.

can any one help me with the wiring for that? A basic drawing that I could follow:

Its 12v dc power supply to power 12v leds. the led's will be wired to a terminal block. can any one advise how to wire the relay? switch? to rx? and finally to terminal block?

thanks
billy

Quote:

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mosfets would be a bit trickier as you have to match up the right voltages.

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On the low current side or the business side?

If you want it RC then you will have to use an RC relay. The method that I described earlier in the thread will keep the lights lit for the whole time that the robot is powered. Second method easier to do and cheaper.

thanks for the help guys.

next question
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I'm going to make a siren for the bot using a high and low 12v car horn( non air type). How would I be able to create a dealy between each horn for example.

The switch is on ( ie power goes along the cable) but i would like the power to go to the high tone horn first for one second and then go to the low tone horn for one second and then it starts over again ( making a siren ). How would i be able to make this work? would i need a delay unit?

I can't think what they're called, but the thing that makes Indicator lights on switch on and off in a car (some sort of relay) would do it I think......

how do these work?

http://www.ebay.co.uk/itm/DC-12V-Del...item23125e8116

If I were to set this for a minute would this delay the power/current? - I mean would it wait a minute before my LED's would get turned on?

or is it the opposite? it would keep the LED's on for a minute? then turn off?