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Archive for the ‘Electronics’ Category

Repairing the Advance Electronics SG62B signal generator

Posted by aonomus on June 5, 2010

… also known as repairing vintage equipment made before you were born.

A friend approached me to take a look at his old RF signal generator, good for 150kHz-220MHz. According to him the RF output frequency ‘drifted’. Armed with the sliver of information, and with no service manual in hand I set about trying to repair it

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Dealextreme LiFePO4 batteries and a GT Power A8 charger update

Posted by aonomus on June 5, 2010

Months ago I wrote a review on the GT Power A8 with a few charts of battery charging/discharging, namely on a NiCd battery pack and a single LiFePO4 cell. Recently I got around to assembling the remainder of my Dealextreme LiFePO4 packs into a 4S1P battery pack with balancing lead and set about testing both the charger and the batteries.

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LED Ring light for macro photography

Posted by aonomus on May 19, 2010

So for a long time I’ve had my Canon S5 IS camera capable of macro and ‘super-macro’ (focusing down to 0mm from the lens), but the main problem that exists is the lack of sufficient and even lighting on the subject to produce a quality, low noise, sharp image. Since ambient light typically comes from above the camera, the lens itself produces a shadow below the camera which is visible in these close up photos, a typical solution is to use a ring flash or ring light around the lens to provide even lighting coverage of the subject.

Instead of spending a few hundred dollars on a ring light or flash by Canon, I decided to hack my own. Since my camera already has a 58mm lens tube adapter and UV filter, I decided to laser cut an acrylic ring, sand one side to a ‘frosted’ finish for light diffusion, and glued a common 60mm LED ring light (runs from 12VDC unregulated) onto this acrylic ring. After sanding the inner ring for a friction fit, the ring was press-fit onto the UV filter.

Press fit LED ring onto the lens adapter/filter.

This sample image shows just how even the lighting is at close range in the foreground

Here is another sample close up image showing a 9V battery with background lighting, with and without foreground lighting from the LED ring light.

I plan to order in another 58mm lens adapter and a UV filter so I can simply swap the regular lens tube for the macro-light version without needing to screw and unscrew the 58mm UV filter repeatedly.

Another improvement is to properly terminate the power cable on both ends, and possibly make a small belt-pack with a battery. The lamp draws 180mA at 12V, thus 2.16W; using a small switch mode circuit I could probably make a 2xAA to 12V dc-dc converter. Another alternative is to use 14450 sized Li-ion batteries (same as AA), and design the switch mode circuit to use either AA or 14500 batteries (2.7 vs 1.5V per cell, input range varies but output should remain at 12V).

Total cost, about $10 ($8 ring light, $1-2 acrylic) plus the cost of the new adapter and filter.


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Vacation and Goodies Upon Return

Posted by aonomus on May 17, 2010

So you may have noticed that I’ve been away for 2 weeks on a trip to Hong Kong/China, and a writeup of my travels is pending, but until then enjoy this photo of the goodies I have returned with.

The goodies:

  1. KG-UVD1P hand held transceiver and spare battery with charger and car adapter (not battery eliminator)
  2. 2x 4 position 2 axis joystick, 2x 2 position 1 axis joystick, 2x 2 position 1 axis joystick (momentary)
  3. 2x CM300DY-24H IGBTs
  4. Ultrafire C2 flashlight (single mode) with Cree Q5 emitter (200lumen approx), 2x 2400mAh protected batteries and charger
  5. 12V 20A SMPS
  6. Digital thermometer with K-type thermocouple (real cheap, only about <$8CAD for the whole kit with a case)

I also picked up a little ring of LEDs that approximately fits the lens adapter on my Canon S5IS camera, configured to run off of unregulated 12VDC, I plan to make a little battery pack and extension wire to let me do evenly lit macro photography without the normal lens-tube shadow that you’ve seen before in my photos. I need to laser cut an acrylic ring to get it to fit onto the lens tube as well (plus a diffuser), but more on that later. For now, a rough test shows that this idea works.

Yes, my desk is that dusty, especially after not touching it for 2 weeks.

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DIY Syringe Pump Version 3!

Posted by aonomus on April 2, 2010

So after a completely failed iteration of the syringe pump (constant jamming of the syringe plunger, hair pulling, etc) that followed the first pump, I’ve come up with a much more compact syringe pump that fits onto a standard project case.

The main difference between this version, and the previous version is the orientation of the mechanisms. The original had the stepper motor behind the plunger, while this version has ‘folded’ in on itself, and has the stepper motor underneath the syringe. The effect is a compact syringe pump that does not take up the entire desk.

The next step is to bolt the pump assembly down onto the case, design the software for a PIC based controller for standalone operation with optional external control, and actually use this for microfluidic devices.

Posted in Chemistry, Electronics, Projects, Science | Tagged: | 4 Comments »