I made this tool so I could discharge the large capacitors I’m using in a controlled maner as just shorting them with a screwdriver leads to big sparks and contact errosion.
It’s simply a 10 Ohm 50 Watt power resistor attached to a nice thick cable and some crocodile clips all with plenty of heatshrink. I settled on 10 Ohms after doing a few rough calculations given the level of voltage I’d be using it at.
I’ve begun to work on motorizing the turret side panels, allowing them to be open and closed just like the turret in game.
Below is the servo and a rough linkage I made out of plastic.
I’m not sure how well this style of linkage will work but that’s what experimentation is for.
Here is a brief update on the portal turret. I’ve talked about it at each open day but I’ve finally designed and 3d printed a reflector that matches the new LED array to the Fresnel lens and LCD.
Side by side you can see the extra length required match up with the new LED.
Coating the inside of the new reflector I’ve done some quick tests in a bright room and the output seems considerably brighter but the real test will be when it’s all bolted back in the turret frame.
Next task shall be relocating the HDMI connector and fixing the LED array and heatsink permanently to the projector housing.
This time I have upgraded to metal geared servos however they are still locked to +/- 90 degees and so they need modifying for continuous rotation.
Here I am using 2.2k ohm 0.1% tolerance smt resistors to replace the potentiometer and trick the servo into thinking it’s locked in one postion.
Last time I used some random through hole resistors I had lying around and when it came to trimming the servos there was a lot of drift, far more than I could correct for, so this shall be a big improvement.
Tiny!
Here is the new chassis after printing, I’ve made a few changes to improve the strength where needed and cut some excess weight.
And side by side with the old chassis.
Before plugging in and testing this radio I replaced some choice components to improve the safety and reduce the chance of damage to other parts of the radio.
The original mains cable was the old twin core single insulation type and had become cracked and hard.
The capacitors replaced were the mains line-to-line cap, aerial-to-chassis earth and the audio output capacitor.
The chassis was very dusty and dirty so I gently cleaned it with a paintbrush and vacuum cleaner.
At this point I also removed the valves for cleaning and inspection.
This is my first project in the world of valve based equipment and I’m very excited to be working on it.
I bought it as a non running chassis from eBay but it seemed to be relatively complete, missing only the outer body. This won’t be a problem as you will see since I intend to laser cut a perspex case for it.
Setup and ready to wow some future undergrads
Will have to use a proper projector screen next time and see if that improves the colour / brightness.
A dash of black n white paint and the turret begins to look like an apple product.
It was also at this point I 3dprinted a white ring to hold the red leds that form the eye.
