Weird voltage from switch single pole switch

[Joethemechanic]

What do you mean by code?

For CW communications. Talk to the other side of the world using just a couple watts

 

[hbiss]

When I was in high school electronics class in nineteen hundred and seventy six. We had to draw a schematic for a superheterodyne radio receiving apparatus with a pencil and paper from memory in order to pass the course.

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Unfortunately younger generations are not taught stuff like that anymore. It's really a shame.

BTW I doubt I could do it now

I doubt I could do it then if they were looking for a specialized communications receiver like that. An all American 5, no problem.

-Hal

 

[hbiss]

You mean like a “voltage pull-down circuit?” Such as how some automotive vehicles would use a computer module to send out an open circuit voltage from a resistor in series to a switch for a door window.

When the switch is pressed the circuit completes and voltage drops to near ground low potential but draws a current

Wave shows as a square DC wave signal to be used by computer to send power to window motor from another circuit

No!

-Hal

 

[Joethemechanic]

I doubt I could do it then if they were looking for a specialized communications receiver like that. An all American 5, no problem.

-Hal

Could you still do it? I haven't built a receiver of many kind since school, and that was almost 50 years ago. The only real thing I've done with radio since then is get my general class license. I've built a lot of antennas even some 160 meter dipoles. I was going to build an amplifier, but once I got the hang of it, I realized that I can communicate with people on the other side of the earth with 100 watts or less

 

[winnie]

What do you mean by code?

Morse code.

Sometime called 'the original digital mode', meaning a method of communicating information using discrete radio signal states.

 

[Jpflex]

Morse code.

Sometime called 'the original digital mode', meaning a method of communicating information using discrete radio signal states.

Ok I was thinking Morse code but now of days I know little about code programming

 

[hbiss]

Could you still do it?

Problem is getting the parts- two section variable tuning capacitor, 455Khz IF's, etc. Tubes are easy enough. Likely today what you will find is all of that on a single chip. No thinking required.

-Hal

 

[Joethemechanic]

two section variable tuning capacitor

I helped my friend's daughter build a crystal radio for her 5th grade science project. She had some kind of store bought kit and it was more or less worthless. The variable tuning capacitor was tough to find. Her uncle owned a auto salvage yard and I thought I'd find one there no problem. Yeah right, think again Joe. Finally some older guy that owned a garage came in to buy parts said "I think I might have one".. Yep he came back with one about 1/2 hour later and gave it to her. That had to be at least 15 years ago. She won 1st place at the science fair, she was so happy.

When I was in 5th grade you could scrounge up everything to build a crystal radio by walking around the neighborhood on trash night

 

[Frank DuVal]

You mean like a “voltage pull-down circuit?” Such as how some automotive vehicles would use a computer module to send out an open circuit voltage from a resistor in series to a switch for a door window.

When the switch is pressed the circuit completes and voltage drops to near ground low potential but draws a current

Wave shows as a square DC wave signal to be used by computer to send power to window motor from another circuit

No! What is meant is just like the lighting circuit you are working on.

It is a load, not a voltage pull down circuit. Just like a light bulb is the load in your lighting circuit. And a multiple bulb lighting fixture has multiple loads connected in parallel. Now there is another resistor connected across the wires under test. That capacitance coupled stray voltage has no power, so the voltage drops to zero (OK, millivolts) across the ~3K ohm resistor.

 

[LarryFine]

My $ 0.02 worth:

Tube electronics are high-voltage/low-current circuits, and volt-meters were designed to have high-impedance inputs to minimize the meter's effect on the circuit under test.

When working on power circuits, we are checking for the presence or absence of "real" power, so we want the meter to indicate only low-impedance, "real" power sources.

 

[Joethemechanic]

Tube electronics are high-voltage/low-current circuits

For a minute I thought we were going to discuss VTVMs

 

[hbiss]

I helped my friend's daughter build a crystal radio for her 5th grade science project.

When I wasn't married yet I thought I would save parts to build a crystal radio and other things for when I had kids. It would be nice to get them interested like I did at a young age. WRONG! All they do is hold their iPhones in their hand and couldn't care less about building anything or how anything works.

-Hal

 

[LarryFine]

When I wasn't married yet I thought I would save parts to build a crystal radio and other things for when I had kids. It would be nice to get them interested like I did at a young age. WRONG! All they do is hold their iPhones in their hand and couldn't care less about building anything or how anything works.

-Hal

So true. We used to build our toys; now, we just buy them.

 

[ptonsparky]

So true. We used to build our toys; now, we just buy them.

I don't know how many hours I've spent inventing and building stuff I could have bought. Then had cash and time for beer

 

[Joethemechanic]

When I wasn't married yet I thought I would save parts to build a crystal radio and other things for when I had kids. It would be nice to get them interested like I did at a young age. WRONG! All they do is hold their iPhones in their hand and couldn't care less about building anything or how anything works.

-Hal

Funniest part was her dad sneaking into the schoolyard at like 4AM to hang a wire in a tree for an antenna , and driving a piece of copper tubing for a ground. He even had a gallon of salt water to improve the ground. He figured if he asked first, they would say no. Nobody said a word about it.

I was driving the get away car lol

 

[Frank DuVal]

In high school we had an amatuer radio club and a room for equipment. One student had a parent working for the phone company. One day we had a wooden pole for antennas just a few feet from the building where our room was. I have no idea if any permission was asked...

 

[Jpflex]

When I wasn't married yet I thought I would save parts to build a crystal radio and other things for when I had kids. It would be nice to get them interested like I did at a young age. WRONG! All they do is hold their iPhones in their hand and couldn't care less about building anything or how anything works.

-Hal

Sad but true. Either robots will take over workforce or by the time the young generation are at the to work, companies won’t be able to fill work demand for skilled learned labor