Sorry. Edited post with schematic but must have been after you looked at it.
Solved the problem with a pullup res. Take a look and at following post to that.

A-A just to be sure not to over voltage tx-2b. Now take a look at new jpg. Removed a couple components and somehow blew the zener open circuit and pumped 7+ volts into tx-2b. can't find solder shorts etc, so may be coincidence. I've got another tx-2b if its blown but no zener low enough and can't remember how to wire transistor as zener. Is it base joined to emitter and z across collector emitter (npn). Live out in the sticks - have to buy on internet, postage etc for small orders here are ridiculous, so may have to wait a while.

Worked a treat though. late here so logging out now.
Dave

thought - might find a 7805 some to rig something.

Attached Images

dragonfly tx new.jpg (32.4 KB, 7 views)

 

The base-emitter diode of a silicon transistor has a max reverse voltage rating of only 5V because it has avalanche breakdown (like a zener diode) at about 7V. If you include the collector-base diode in series then the voltage is about 7.7V.

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Uncle $crooge

 

Thanks for info Audioguru - you can do positive comments . I know these things are cheap, but not everyone can afford expensive planes and may want to copy what I've done.

Realise now though I didn't need to disconnect transistor/diode anyway! Will replace zener and put tx-2b in socket.

Dave

 

Model airplane clubs have a group of guys who fly tiny lightweight RC planes in school gyms. Many use the simple radio control electronics that come in $10.00 RC mini cars.

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Uncle $crooge

 

Agreed.

Perhaps I'm wrong but I didn't think they used proportional motor control - its not available directly through the tx-2b. The tx-2C has a sort of pwm control on one pin but I think it just gives 50% cycle. A lot of sellers of these toys claim proportional control for stuff with only 2 or 3 set speeds.

David