After more than a month of video-making abstinence I finally managed to make another one.
It’s about the classic Heathkit IG-102 signal generator. 2 Tubes, the 12AT7 and the 6AN8 make up 4 oscillators (3x RF, 1x internal modulation). Some little hack at the end…
if you need some manuals I probably can help you. I can’t put up any manuals ’cause Heathkit was a little cranky about that sort of thing – so until the situation is clear, just ask.
So currently I’m testing several different approaches on generating the HV for the scope project. This is my favourite for it’s simplicity. The schematic is Here:
Be sure to use a very good cap, that can withstand the hight currents when discharging. The parts are not critical, any transistor, that can handle the power will do and the resistor values are just for orientation.
Have fun watching!
The whole arrangement will make a top voltage of about 400 V with two secodaries at 24 V, you can go muuuuuuuch higher with lower values and resistor values. In my very first tesla-coil almost the same arrangement makes somewhat 4 KV.
Yeah this means we will have some more TV, when the undead arise!
This is a super simple setup – with only one flaw: under most jurisdictions it is illegal 🙁
But if we replace the Antenna with a wire and a 10 to 100 Megaohm resistor we are all good to go!
So come on Zombies and give me a chance as a program director 😀
Good ideas not always turn out for the best but have some value anyway.
The two trafos you see are way to “soft” and at 200 mA the output will drop from 220 VAC to 210 already.
Nevertheless it works fine until that and I will just have to wait and see if some better trafos find me.
I just made up some working test setup for the homebrew oscilloscope project and the screen came to life for the first time:
Here is my setup:
By the way is the 3KP1 / DG 7-113 with the green p1 phosphor. If you ever come across the white phosphor (3kp4) you found some nice piece of rareness. The P4 version was used in the Pilot TV-37, one of the first portable TV-sets. Check out David and Marlene McClellans blog about restoring one! Also check out some video of it here.
When I gave myself a little treat (a pack full of scrap electronics for €5) I found a complete DC motor speed controller Kit inside. So I built it up and show how this pwm thing works.
The trick here is, to not control the motor speed by using a lower voltage and therefore putting in less power continuously but to slice up the motors energy input into chunks. That will let the motor run even at lower speeds whilst letting it keep most of its torque. Pictures say more than a thousand words, so watch the vid:
I got myself a little treat (10 Kg of scrap electronics) and inside I found, among other great stuff, a GDR board that was made by RFT. It seems to be some kind of stereo amp or Tone control circuitry because of its symmetric nature.
We have a 2761 Dual opamp and 4 E X3 C36 (?) transistors at work alongside 4 Styroflex(polystyrene) (you gotta love em) caps.
I asked around in my favorite forum where some old-timers hang out and that were in electronics back in the day, when there was the GDR. I’m hoping to find out some more soon and get this thing going!
While I was working on my Oscilloscope project I discovered, that breadboards are only semi-useful for Bigger things. Everything seems not to add to your project but to just pile up on it. After you added some probes and things that need a bus you will sit on a fragile, unforgiving crapstack, that just waits for you to stick a jumper-wire in the wrong hole. So I decided to make myself some room on the board and push connectors, displays and meters away from the center. Just take a look what came out:
check out the vid to get a walkthrough
So here is a little list what it includes:
* 2 max 232 Level converters
* An arduino NG
* 3 BNC connectors
* 8 banana Plugs
* A 50 V voltmeter
* Tiny tiny breadboard for displays and button stuff
* 4×7-segment display with driving transistors
* Datavision DV-20208 HD44780 compatible LC-display
* 2x lm3914 bar-graph displays with jumper selectable voltage range
* Avr-Net-IO for some Ethernet
* A -10V -5V GND +5V +10V earth 0V 35V Power supply
* and of course a humongous breadboarding area
This is of course just a source of ideas so if you make one of your own please let me know and if you don’t publish yourself, I’d be delighted to show off pictures of yours here!
Some words on construction:
The base is made from a piece of structured plastic (45 x 30 cm) on top of that are some pieces of wood with some plastic veneer that form the body. This makes up the wedge form in the back. On top once again I used some sign plastic covered with red spraypaint, why red? because its shiny 🙂
Ground and Earth are normally separated and can be connected on demand.