CTC-10 remote update

[andy]

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[frenchy]

Haven't noticed my dogs doing anything when I activate the remote but I'll sneak up on one of them and put it by her ear and see if it wakes her up!
This is an electronic ultrasonic, has a teeny mylar speaker of some kind that transmits the sound. I may grab a few other remotes to goof around with on this project if the new transistor doesn't do the trick.
On the reverse motor circuit, I wasn't sure how that works either but it may just be something that changes the intensity of the signal and that's how it knows to reverse or not.
I was told the 165V I was reading as in the 60's is probably just due to the high resistance + the meter loading it down. This was figuring in the resistance of 2 meg in the circuit and appx 1 meg of my electronic meter. Does this sound right?

[frenchy]

Originally Posted by bobgary

The schematic states that "voltages measured with "voltohmyst."" That would be an RCA VTVM with an impedance 10 MegaOhms. Your modern DMM should have the same if not higher input impedance. The idea is that you should be able to measure a voltage without the meter introducing any change in the reading.

I dunno... all I know is with this digital LCD meter even if I measured straight off the 175v onto my own 1 meg resistor, it dropped to 88 volts already, and to about 60 if I added another resistor, this is with just 175v to resistors to meter and that's it, only thing involving the tv was the 175v source. So that's when the 'meter is dragging it down' explanations I got sounded like it must be it as there is no other explanation I can think of. I tried a better Triplett meter I have also and it went up about 20 volts, but still only half of the 165v it said it should be with 175v + 2 meg of resistance.

[old_tv_nut]

I had once a Heathkit with ultrasonic remote using that little mylar transducer, and had to replace it twice in about 3 or 4 years. Somewhere else here, though, someone said they never saw a problem with the transducers.

[frenchy]

I've ordered a new transistor hoping that might be the problem. That one little transistor getting juiced from 5 million remote clicks all those years jsut might have worn it out : ) Bro in law told me that indeed if the transistor was toast, it still might just have a tiny bit of juice left in the circuit to work if it was right up to the receiver pickup, like it's doing now.
And also some more precisely correct keyer tubes for the remote chassis, will see how it goes after that's all slapped in there.

[nasadowsk]

heh
Hope modern transistors don't wear out as fast

Imagine if they broke after 1,000,000,000,000,000 or so cycles?

[old_tv_nut]

found a place that sells transducers:

http://www.oselectronics.com/ose_p105.htm

never dealt with them, so at your own risk

[frenchy]

Found the faulty component - my brain!

The problem was just that a few weeks ago when it was still working to a decent extent, I still had the pushbutton faceplate attached, then removed it to clean the transducer screenhole out. So I was just testing it without the faceplate, and no juice... because the faceplate serves as a connection point between the transistor drive and the ground of the transducer! It was barely squeaking because the transducer was just getting slight grounding - from my fingers.
Anyway now it works like a champ from across the room, that totally clogged-up screen was indeed the glitch but it took me a couple of weeks of cussing to find out. Thanks for the tips nonetheless....Frenchy

[old_tv_nut]

Hooray!

Always great when the light dawns on an annoying problem.