Micron receiver as interface - Succesful use of receiver on serial inte

[fighterpilot]

I have succesfully used a micron mini receiver kit as an interface. It's nice not being connected by a cable and I can use any transmitter at all now. Also I realise I can now use my buddy box connection for teaching my son.

I could do with some electronics wizz developing this to take power from the PC is this possible?

[Mike Roberts]

The Micron receiver consumes 3ma. You might just get this from the serial port. You are helped by Micron including most of a voltage regulator circuit on their decoder board. It uses an NPN transistor, 10uf cap and 4k7 resistor. If you add a 5v6 zener diode accross the cap (transistor base to ground) you have a 5v voltage regulator! Now connect the positive supply to pins 1,6,7 on the serial connector (see my IRQ serial interface on my website) and off you go.

Check the voltage between the serial pins 1,6,7 and 5 (ground). If this is over 7v you are probably OK

Mike

[fighterpilot]

Thanks that sounds really useful. Just 2 questions.
1. Do you mean connect pins 1,6&7 to where the receiver battery would normally go? I think this would then "use" the newly made voltage regulator.

2. I currently run from a battery, connect +ve out of the micron part volt reg (the red wire between boards) via a resistor to pin 9 of serial port, and connect the composite baseband signal to pin 5. i.e the receiver is "floating" and I switched the connections to invert the signal. So to use the serial port to power the receiver, I will have to connect -ve supply to pin 5 and invert the signal using 1 transistor stage.
I think I know what I mean...sorry.

[Mike Roberts]

Have a look at the standard IRQ serial interface circuit diagram on my website. This shows how 1,6,7 provide power. You should connect the positive supply from the outlet of the diode to the Micron v reg. transistor collector.

Ground is pin 5 as you say.

You could probably use a 1 transistor interface powered from the Micron 5v supply. If you find this does not work you will have to move to the full 2 transistor IRQ interface. Don't worry about signal direction (inverting etc). The timing between successive positive edges is the same as between the negative edges.

Cheers

Mike

[fighterpilot]

Thanks Mike
That gives me the confidence to carry on, although from past experience I'm not very good at going the last mile once I've got something working in a fashion.

Finaly - someone suggested I shouldn't use the Tx with the RF enabled and the aerial down for long periods, because of reflected power damaging the output stage. Any thoughts?

Thanks again
Chris

[Steve Lewin]

It's not a brilliant idea to be radiating RF with the aerial down. I think that's why sim connections via RF have never really taken off.

Steve

[Mike Roberts]

Yes it is not recommended to run for long periods with the aerial down as this puts the output stage out of balance and can increase the heat generated by the output transistor.

Cheers

Mike