So went through many boards trying to get useful results from thermopiles. The trick is they have the teeniest tinyest voltage changes & very slow responsiveness. Work around the responsiveness through extreme amplification.

The unamplified thermopile was immediately busted. Not enough current.

Straight 2:1 amplifier. The voltage changes were too small.

Difference amplifier. Forget it. The 2 thermopiles aren't matched enough to amplify without serious balancing circuits.

A highpass amplifier started getting somewhere. This is the ideal solution for monocopters. Unfortunately, this thermopile has a 900Hz ripple which blows everything else away when amplified.

The bandpass amplifier was the champion. Mainly, it's a highpass followed by a lowpass filter. You could make a much better filter but we wanted to guarantee it worked & only had 1 capacitor value.

This gave a 0.1V wave corresponding to the rotation. That's 5 bits of accuracy.

Depending on the RPM, you get clear sine waves or noise. Need to increase the sampling rate to know what's going on.


There's still gyros, since we really want indoor capability. You could pick up monocopter roll & pitch on an IMU if it had super high limits, super high dynamic range, & super fast sampling. Maybe the vaporware ITG-3200 will be the 1 to do the job.

There's our ancient IDG300 on the fuselage for a test. Using 1 gyro didn't work out because it has to be exactly aligned to not pick up any yaw rotation. Maybe just an X & a Y would be enough to cancel out the yaw rotation if they were aligned just well enough to not saturate.


Marcy 1 is having a lot of LEDs fail. It's probably from landing on them.

Although we did drive to Santa Clara to get $30 of LEDs, the best place for LEDs is dollar stores. Got 3 5mm white LEDs for $1. Unforunately at this price the 5mm LEDs are no brighter than the 3mm LEDs, just heavier. Now have enough white LEDs to light a runway.

Your goal is to worship the Jesus Heroine.

Shot of the complete avionics except for the POV board.

Finally got some video of Marcy 1 POV flying manually. She was super unstable. Have to work through still more radio problems.

Views: 3150

Comment by Michal on March 5, 2010 at 2:34pm
Imagine thousands of Marcys circling over your head under clear night sky. They are screaming. They are tryin to say something desperatley. And suddenly they stop. OUCH!!! I forgot my helmet....

Comment by Pat Hickey on March 5, 2010 at 2:43pm
I had good luck with an AD623 instrumentation amplifier and the Melexis thermopiles. You can get a gain of 500-1000 with a single 8 pin IC and single gain resistor. The resulting signal from a differential pair of thermopiles will be about 1v peak to peak on a sunny day.

Comment by Mark Colwell on March 5, 2010 at 3:11pm
Was there any wind for this flight test? Why such a fast decent, did a tree grab Marcy ??

Comment by Mark Colwell on March 5, 2010 at 3:16pm
I buy toys for my extra small batteries at $ stores, And they usually have other parts too, but watch out for poor quality USB cables.

Comment by Mark Colwell on March 5, 2010 at 3:20pm
I got a Wow Wee BladeStar at "Ross", (toys for less) for $15. They buy discontinued stuff and sell at good price, but have limited selection, I buy my shoes there too.

Comment by Gary Mortimer on March 5, 2010 at 6:01pm
Keep moving Jack, love it.

Comment by Krzysztof Bosak on March 6, 2010 at 1:08pm
Jack, pls commercialize 10% of your stuff just to get the money to finish the 1st private Mars Lander.
By not selling the results of your work, you are dooming the Western Culture to Eternal Stagflation and Crisis Meltdown.

Comment by Mark Colwell on March 6, 2010 at 7:34pm
Went to local recycle store and found some ultrasonic & PIR human in room detectors to shut off lights, etc. when no one is moving, or in room, for $5 ea I may try to use them for a hight above ground sensors, I will post model data later.. dual voltage 100ac, 277ac 20amp power controller are $5 also...I need some of theses too.


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