Radio control Tx details

Thu Apr 06, 2006 12:43 pm   

Anyone know whether the pots in the Tx are used in "variable voltage
out" form or "variable resistance" form to control the channels? I
presume, due to 3 wire connection that its the former but id be pleased

if someone could confirm? Im looking at hacking one and applying
varying voltages to the pot outputs from a uProcessor/DAC.

Ta
J

Fri Apr 07, 2006 9:20 am   

On 2006-04-06, Coyoteboy <coyoteboyuk_at_hotmail.com> wrote:

possibly... could be neither.


measure the the input to the tranmitter and get the micro to copy that signal.

Bye.
Jasen

Fri Apr 07, 2006 10:26 am   

Jasen Betts wrote:

What else could it be?


Well thats the plan but i was just hoping someone would have already
worked on them and know but theres little evidence on google so I'll
have to crack out the scope.

Ta
J

Sat Apr 08, 2006 8:08 am   

On 2006-04-07, Coyoteboy <coyoteboyuk_at_hotmail.com> wrote:

could be something like this +v
|
|
.--/\/\/\-----|--+-->|-----------.
| | | |
| .---------+ `--|<---/\/\/\--'
| | | ^
| | . . . .|. . . . |
| | . VCC( . |
| | . . |
| `---RES(4) OUT(3)------+-----> out
| . 555 .
+-------TH(6) DIS(7)--
| . .
+-------TR(2) CV(5)--
| . .
===== . GND(1) .
| . . . .|. . . .
| |
`-------------+
|
gnd


15 years ago they were using frequency and duty cycle modulation of a the
input signal, this was used to amplitude modulate the carrier

these days AIUI many setups use digital encoding signalling.

Bye.
Jasen

Sat Apr 08, 2006 6:13 pm   

On Sat, 08 Apr 2006 08:08:33 -0000, Jasen Betts <jasen_at_free.net.nz>
wrote:


---
That's not neither, it's using a variable resistance to control the
output, which is one of the options the OP suggested.

--
John Fields
Professional Circuit Designer