Remote control problems

Thread Starter

rjjenkins

Joined Apr 16, 2011
143
Please would you have a look at the attached circuit (hand drawn, sorry)

It's intended to drive a lamp using a remote control unit. The unit is this one

http://www.ebay.co.uk/itm/433MHZ-4-Channel-RF-Radio-Wireless-Controller-Remote-/320922756827?pt=UK_Gadgets&hash=item4ab87ca6db&_uhb=1

I want to run the lamp and remote on different circuits and isolate them using a 4N25, and to drive the lamp using a mosfet.

The remote unit toggles, so that pin 7 of the rx goes high when the tx button is pressed and stays high until it's pressed again. This all works fine. However, the lamp only stays on so long as the button is pressed, i.e. it does not toggle.

What am I doing wrong please?
 

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tubeguy

Joined Nov 3, 2012
1,157
If the lamp lights when Tx is pressed but turns off when released, the circuit is working, just not toggling.
Post a datasheet for Tx/Rx.
 

Thread Starter

rjjenkins

Joined Apr 16, 2011
143
If the lamp lights when Tx is pressed but turns off when released, the circuit is working, just not toggling.
Post a datasheet for Tx/Rx.
There is no datasheet unfortunately. However, the remote itself DOES toggle - i.e. if I disconnect it from the rest of the circuit, it works perfectly. So it's something between the rx and the lamp that is not right.
 

tubeguy

Joined Nov 3, 2012
1,157
There is no datasheet unfortunately. However, the remote itself DOES toggle - i.e. if I disconnect it from the rest of the circuit, it works
How are you determining it toggles when disconnected?

It may be Rx can't properly drive the Led in the 4n25
 

tubeguy

Joined Nov 3, 2012
1,157
Have you actually connected an LED with a 360 ? ohm resistor to verify this works ?
 

Thread Starter

rjjenkins

Joined Apr 16, 2011
143
Not with the resistor actually, no. I will. I think maybe the resistor is too high.
 

Thread Starter

rjjenkins

Joined Apr 16, 2011
143
I've shorted out the 380 ohm resistor on the circuit and it now works, so I guess the rx output was just too feeble. Am hoping that it's not now too much for the LED but I suspect not.
 
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