Solder Pot

I recently acquired a cheap 200 watt solder pot to speed up disassembling old electronics, it took 600 grams of solder to fill... its quite deep, i might consider stretching the amount of solder using steel ball bearings if if have to refill it.

The element is regulated by a simple triac circuit, there is nothing to stop it from overheating and no real way to precisely control the temperature, also the base is small and the entire thing is top heavy when filled. After the solder is completely filled i turn it down almost as it can get, anything higher causes the solder to rapidly oxidize.

After an hour of messing around with it im pretty happy with the results, and i have a good future project of building a digital temperature control and a larger sturdier base, the electronics are currently right beside the element and will most definitely fail rather quickly if i let the thing overheat.

Projector Update

I finally finished the project, i am quite happy with the results and now have plans to improve the concept with brighter light sources. Im thinking either 12v hid automotive lamps or higher power leds.

Control Board

The control board consists of a pic12f675, a relay, npn transistor, a protection diode for the relay and some resistors... nothing particularly special.

Code

#include <htc.h>
#define _XTAL_FREQ 4000000

__CONFIG(MCLREN & UNPROTECT & BORDIS & WDTDIS & PWRTEN & INTIO);

void main()
{
    TRISIO = 0b111100;
    ANSEL = 0;
    while(1)
    {
        GPIO = 0b000010;
        // wait for power on signal, 5 seconds long
        for(int x = 0; x < 2000; x++)
        {
            __delay_ms(1);
            if(GPIO2 == 0) x = 0;
        }
        GPIO = 0b000001;
        // wait for ~1 ms pulses to stop, after 100 ms of nothing turn off
        for(int x = 0; x < 100; x++)
        {
            __delay_ms(1);
            if(GPIO2) x = 0;
        }
    }
}

High Power Led

The led and power supply came in, i wasn't expecting how bright these things would be. Everything came together perfectly somehow...

I mounted the led onto an aluminum heatsink with some screws and some thermal silicone adhesive, to mount the whole thing into the projector i removed the top part of the bulb cage and cut out the section that screwed onto the projector. I happened to have a collimator lens i salvaged from another projector that fit on top of the reflector, with the reflector and lens siliconed down it was ready to install. A note of warning, the power leds tend to have a silicone lens injected over them which is quite fragile and easily peeled off. I almost had this happen when my reflector came off and the silicone i used bonded to the lens!

Its not quite as bright as the uhp bulb but that could easily be fixed with an led with a higher output

Power Supply

The power supply was based on an st micro TSM101I voltage amperage controller, i used a simple hack using a 100k resistor and a 10k potentiometer to fine tune the amperage supply so the led isnt over driven and die prematurely.

At 1.7 amps the heatsink provided (if you can call a thin piece of aluminum one) got quite warm, i found an aluminum heatsink of the perfect dimensions. I siliconed the heatsink down so it wouldn't shift and mounted the power supply using silicone thermal adhesive

Testing

Surprisingly everything worked perfectly, the projector turned on and off just as it would before. A slight disappointment was the fact that  the led was not as bright as i hoped it would be, it ended up producing an image about as half as bright as it originally did. This is with the brightness of the projector turned all the way up.

The projected image is a bit brighter and has proper color, my camera sucks for these types of situation.

Conclusion

For about 50 dollars (including consumables) i retrofitted the projector in about 2 hours of solid work and 4 or 5 hours of figuring out the basics of pic micro controllers. For a bit more money a much brighter led can he had that would make this more worthwhile. Considering how much longer an led will last compared to the ~2000 of a uhp lamp and the power savings. Power loss from the conversion taken into account powering the led comes to about 30 watts, one quarter of the power consumed by original bulb.

Projector LED Mod

I happen to have a stack of old Phillips 3 lcd projectors, the ones i repaired work great... but only until the uhp bulbs burn out and at a hundered bucks a pop minimum to replace, probably more considering the age of the projectors its really not worth the price

Now if i were to replace the uhp bulb and high voltage board with a high power led for a fraction of the price that would be worthwhile, especially considering how much longer the led will last compared to the 2000 or so hours from a uhp lamp.

Some quick poking around the insides of any of the projectors resulted in a 3 wire connection from the high voltage supply to the control board. Probing with a dmm showed 5 volt signals, further probing with an oscilloscope showed that the control board pulses a high signal to start the hv board which gives a constant low while the bulb is running. While the bulb is active the control board gives a continuous pulsed signal, when that signal stops the bulb is turned off.

Pretty straightforward so far, 40 $ worth of parts are on their way and i have already figured out how i am going to implement control using a pic micro controller.

555 Timer Contest Entry: EL Inverter

This project actually started before the contest was announced, its purpose is to provide a simple tunable circuit to drive EL components. Most drivers you can fins will only provide enough power to light a few feet of EL wire and drive at a static frequency. I wanted to observe the color shift that occurs when driving at higher frequencies.

The circuit is a simple 555 timer in astable mode with a 10k potentiometer to adjust the working frequency from around 150 to 3000 hertz. The output is used to switch a tip122 power transistor which sinks a transformer that produce close to 100 volts ac. Please note that many audio transformers are potted with a low melting point wax and can get warm enough to leak and fill the holes of your breadboard!

 

The only difference between the circuit i designed and what i built is a 10 ohm power resistor between the emitter pin of the power transistor and ground to prevent it from sinking too much current and overheating.

The transformer im using is an old 5v wall wart transformer being run backwards.

The circuit works perfectly as expected, although since the duty cycle is not constant the voltage does increase a fair bit as the operating frequency increases.

A nice color shift from aquamarine to blue is observed when adjusting the frequency above 2000 hertz.

Giant Breadboard

I always seem to quickly run out of breadboard space, even with simple circuits...
With ten 6.5" * 2.125" breadboards anything requiring more space might as well have its own custom pcb

Camera Update

After several months of patient waiting i now have a set of microscope objectives (4x, 10x, 40x and 100x oil) and an m42 to rms ring (i wanted it for a mounting platform rather than for my current camera)

 

So far i have significantly higher magnification than was ever possible with my Helios 44-2

Taken with 4x lens

Taken with 10x lens

I am having trouble with the 40x and 100x objectives though, i am quite sure that the focusing strength of the lenses are high enough that i need to position the sensor even further back. I made this assumption when i looked at the camera configurations for trinocular microscopes. So far im getting some awesome results, going even further i purchased a slide micrometer to determine the scale.

Helios 44-2

4x Objective

10x Objective

 With a bit of rough calculations it works out to 3.5 px \ 0.01mm for the Helios, 10.7 px \ 0.01mm for the 4x and 26.5 px \ 0.01mm for the 10x objective... i really want to get the 40x and 100x objectives working now.

Huge Eprom Eraser

Over the past year i joined a small hackerspace that was just getting on its feet, one of the major initiatives we have going on is recycling... or what recycling really should be. In that time i have collected over a hundred eproms and i really should do something with them. I already have a chip programmer but lack the necessary eraser needed to prepare the chips for programming.

Naturally i went online to see what was out there... for 5 to 20 dollars i could get an eraser with a capacity of 2 or 3 chips. That won't do the trick if i want to batch test a few hundred of these things. The solution came when i found an old florescent blacklight in the corner, it drives f15t8 bulbs and i can easily get g15t8 bulbs which emit light in the crucial UVC spectrum.

The only real issue is the fact the UVC spectrum is very dangerous, enough to cause burns to the skin and your retina! I chose to use a cheap metal toolbox as an enclosure and sealed every seam to prevent light from escaping.

The rest was just dismantling the old light for the parts i needed and bolt them to the inside of the toolbox.

I used an old spring wound timer to control the time of exposure and added a safety switch to cut power if the door was open.

 Also i added a tiny plastic window so i could see if the bulb was working, UVC light won't pass though, pretty much the only thing it will pass though is quartz. Everything works fine so far, it takes about 7 minutes to erase a 27c512 eprom. I will run more detailed tests when i have the free time.