Category Archives: Uncategorized

Solar Evacuated Tube Collector (ETC) technology

Over the weekend we have almost perfect sun shine. So I collected some data on a 20 Tube solar collector. Here are the results.

Temp inTemp outdifference

The pump rate was at 6 liters per minute (0.1 liters second). So give this its possible to work out how much of the suns energy was being captured. We just need to know one more thing. The specific heat capacity of water. Which is 4.2 Kj / Kg / degree C. That is 4.2 kilo Jules per kilogram per degree C.

So the calculation turns out to be.

Total Energy per second = (Specific heat capacity of water) x (Liters per second) x (Temperature difference)

1.68 kW = 4.2 * 0.1 * 4

Microwave repair

It turns out that a microwave can be easily fixed. The symptoms are luke-warm food.

Here from the image above you can see the cracks in the magnets. These develop because the heating and cooling of them over time fatigue the fragile compound they are made from. I therefore, bought a new Magnetron (love that word) and plugged it in. It has now been working for over a year without issue.

Quad copter designed for flight longevity

The specification of the quad are as follows.

Load: 10.64 C Voltage: 14.28 V Rated Voltage: 14.80 V Energy: 62.16 Wh Total Capacity: 4200 mAh Used Capacity: 3570 mAh min. Flight Time: 4.8 min Mixed Flight Time: 16.9 min Hover Flight Time: 32.9 min Weight: 452 g   15.9 oz
 Motor @ Optimum Efficiency Current: 4.68 A Voltage: 14.55 V Revolutions*: 4886 rpm electric Power: 68.1 W mech. Power: 59.3 W Efficiency: 87.0 %  Motor @ Maximum Current: 11.18 A Voltage: 14.21 V Revolutions*: 4274 rpm electric Power: 158.9 W mech. Power: 129.1 W Power-Weight: 508.3 W/kg   230.6 W/lb Efficiency: 81.2 % est. Temperature: 43 °C   109 °F  
Wattmeter readings Current: 44.72 A Voltage: 14.28 V Power: 638.6 W
 Motor @ Hover Current: 1.63 A Voltage: 14.71 V Revolutions*: 2027 rpm Throttle (log): 26 % Throttle (linear): 44 % electric Power: 23.9 W mech. Power: 19.4 W Power-Weight: 77.1 W/kg   35 W/lb Efficiency: 81.2 % est. Temperature: 28 °C   82 °F specific Thrust: 13.05 g/W   0.46 oz/W  Total Drive Drive Weight: 1069 g   37.7 oz Thrust-Weight: 3.5 : 1 Current @ Hover: 6.51 A P(in) @ Hover: 96.3 W P(out) @ Hover: 77.8 W Efficiency @ Hover: 80.7 % Current @ max: 44.70 A P(in) @ max: 661.6 W P(out) @ max: 516.2 W Efficiency @ max: 78.0 %  Multicopter All-up Weight: 1250 g   44.1 oz add. Payload: 2541 g   89.6 oz max Tilt: 71 ° max. Speed: 40 km/h   24.8 mph est. rate of climb: 5.0 m/s   984 ft/min Total Disc Area: 58.58 dm² 907.99 in² with Rotor fail:

RCTimer motors 5010 motors 360

17″ Carbon fiber propellers blades.

Carbon fiber frame

Here is the eCalc link to an online calculator that can be used to approximate the build and estimate its flight capabilities.

Roland dg dxy-1300 firmware exploration

I have extracted the ROM images from the two 27C512 chips inside the DXY-1300. I then passed them though a disassembler. This produced the asm files respectively below.

RolandDG_R15209223_LH53140H_8949E is the more interesting because it contains z80 code that starts at 0100h.

The asm files have beep passed as all code. However they need to be separated into data and code. As there is HPGL data starting around E000h in the R15209223 file and likely numerous other sections. This HPGL is the test image that is drawn when the device is powered on holding down the enter key.

boot sequence log

The goal for me is to use my Z80 ICE debugger from Tauntek to analyze the memory until its booted.

An objective is to change and find how the pen speed works. As I have a laser burner I want to mount on it.

0100h is the default place the z80 jumps to for execution and called the ORG. I also expect Ill be able to use the boot test image at location “000e0e0” to print out back engineering debug info.





I am waiting until I receive some new 27512 chips in the post as it appears the originals in the plotter are ROM or in some way not writable by my EEPROM programmer lt866cs.

here Is a simple analysis of the most used sub routine calls within the code. I believe it identifies the main execution loop.

FPV in stanford-le-hope


I woke early today to test video recording with the Raspberry pi. Using the camera module. Here is the video below. It is quite shaky but it was also a bit windy. I would have liked also to use a gimbal to position the camera. I intend to do this using the two extra channels on the transmitter.

Calibration of Gos 658G Oscilloscope

Realising there is no documentation on the internet to calibrate these oscilloscopes.

I have a GOS 653G Or a (ISO-TECH ISR658G) and wanted to calibrate it. Note that powering up the unit will give better calibration results as the CRT warms up and the power supply reach a static voltage. Ensure this is the case before calibration.

Cursors board

Oscilloscope Cursors board Top back

I have identified 5 variable resistors on the cursors board. This is the board that is controlling the cursors drawn on the screen. There are some things one needs to be aware of when trimming these.

1. The cursors need to be at the extremities of the screen as these need to be aligned to the edge of the graticule.

2. These need to be adjusted with caution and in ratio to the zoom variable resistor located near the CRT tube ref.