I came across the Super Probe two weeks ago, and just had to make one. I had a bunch of the PIC 16F870 microcontrollers left over from an earlier project, and the rest of the parts were all easily found in my parts collection.
It is a really simple circuit, with so many useful features:
- Logic Probe (L 3.7 V, P > 0.5us pulse)
- Logic Pulser (0.5 us pulses at 5, 50, 500, 5k Hz)
- Frequency Counter (8 digits)
- Pulse Counter (8 digits)
- Voltmeter (max 5 V, readings are a little high)
- Diode measurement (measures fwd voltage using 5V supply via 10k resistor)
- Capacitance measurement (1nF to 500uF, approx 100pF resolution)
- Inductance measurement (100uH to 999.99mH, but not very accurate)
- Signal generator (0.5 V square ware @ 500 Hz)
- NTSC video generator (white dot pattern)
- ASCII test pattern (A-Z then CR/LF at 1200, 2400, 4800, or 9600 baud)
- Midi test output (plays middle C on selected midi channel)
- R/C servo test output (approx 770 to 2300 us pulses @ ~28 Hz for servo control)
- Square wave output (1 to 9999 Hz 5V square wave)
- Pseudo random output (10 kHz PRNG)
- IR test output (38 kHz 50 % duty cycle square wave for IR receiver testing)
- PWM test output (6 kHz square wave with 3 % to 97 % adjustable duty cycle)
In addition to the PIC, you just need 4 common anode 7-seg LED displays, a 20 MHz crystal, and a few resistors, caps, etc.
I found the display to be a bit dim, but the MAN6610 7-seg displays I used were quite old and would be rated quite low in brightness. I left off the LM2931 regulator as I will just power it off 5 V, and so I actually put a PIC ICSP connector on the end of the board for re-programming, and an easy way to connect power.
We are looking to make up a PCB for this so that members can make their own. It is a bit of a pain wiring up the 7-seg LED’s (using the LTC4627 would help a lot).
Over the last couple of months, Gav and R3becca have been discussing a new project idea - the Geigerduino. The idea being to be able to build an simple device that can detect cosmic rays or other radiation using a Geiger-Müller tube and an Arduino, and then publish the details so others could do the same.
In late August, whilst having an R&D group dinner at Rockdale McDonalds, Gav quizzed me about generating high voltages, and I drew a rough schematic of a DC/DC boost converter (on a napkin of course). He told me the goal was to generate a PWM controlled voltage of up to 1000 V, using USB as a power supply. Having planted the seed, over the next two weeks I did some additional research and realised we should try a DC/DC converter using an isolated transformer with a voltage multiplier to get this kind of output.
So, two weeks ago, we began prototyping this at the space. I built up a simple circuit on a breadboard, using a small transformer, some high voltage diodes and capacitors, and a MCP14E5 mosfet H-bridge driver chip. I had acquired a small batch of these transformers from a surplus electronics place a few years ago, and they seemed appropriate with a DC resistance of 11.5 ohms on the primary, and 2,300 ohms on the secondary. I had no other specs, but I think they were intended for generating HV to drive EL or CCFL lighting. The MCP14E5 is actually intended to drive the gate of power MOSFETs, but I had it handy, it is fast and can supply significant current, and it seems to do the job.
I also needed a signal source to drive the transformer, and seeing as R&D had recently done a group purchase of Bus Pirates (preorder 2), I decided to use one of those. The Bus Pirate has a PWM generator mode that can generate 1 kHz to 4000 kHz signals with varying duty cycles.
So, what was the result - first we tried 1 low frequency, possibly 10 kHz, and got almost 500 V DC out.
A bit of tweaking, and we found that these transformers work best at around 50 kHz. This picture was taken when we were using about 8 V at 200 mA to drive the transformer.
Yes, we are generating nearly 800 V DC using USB and a simple breadboard circuit!
Gavin and I then made up these circuits on some prototype PCB’s, and found we could generate 600 V DC quite nicely from USB power. Gavin even incorporated his Arduino DangerShield for PWM control.
This post is to describe a particularly epic piece of work by one of our members, Bret. He’s built a full-sized flight simulator cockpit in his house! Here’s his description:
The simulator was inspired by a visit to a facility in the north of Sydney which maintains and operates some impressive aircraft (but it would be improper to disclose who that would be :-) )
During a flight in one of their sims, I began to abort a landing since it just wasn’t quite right, and the instructor gently told me that I’d make it in. Only afterwards did I consider what had happened. It was so realistic that my natural piloting sense told me I was at risk, and to get out of the situation as I had learnt (namely to make the engines make a lot more noise, and go around to have another go). My later realisation was that I felt so immersed in the experience that I was as good as flying a real one! So, what other response than to decide to build my own (albeit not quite so complex or expensive)?
The sim is reasonably closely based on a Boeing 777, partly because the www delivered me some sort of ok dimensioned drawings which I was able to work from. Also, the 777 is all glass cockpit, making the instrumentation easier to manage. Finally, the appearance of a 777 is quite close to a 747-400 so I can always make a change in the future if I need to! Boeing or Airbus? Well. knowing a good few Qantas engineering types, they tell me “if it’s not Boeing, I’m not going!”. Decision made!
Technically, the sim is MS FS2004 (FSv9) on one pretty grunty quad core machine, running the flight model and front window view, and the IO and displays for the various parts of the cockpit are shared between 3 other win PCs. Video is the limiting factor for a sim I have found, as long as the main flight computer can handle the “visual experience”. Various freeware applications interface the systems and the aim is to provide a close to authentic experience without ever needing to “touch” a PC, only via the normal aircraft interfaces.
The project started just after Christmas 2008, and progresses in fits and starts depending on how busy life is and what I need to buy next. It is intended to always have it flyable, so that I can’t lose interest!
Recent flights have been Sydney to London and return (flying at the same time as some friends going on holiday) and the weather that is “provided” is very realistic. I landed in thick fog in London (simland) and my mate told me a day later that the real aircraft had diverted to Rome because they wouldn’t be able to get into the real London. That made sense, because I pretty well found the sim runway by braille!
The MakerBot Assembly Day was a rip-roaring success! Thanks to all those who attended and helped our bot crawl into life.
It took us quite a few hours, and a little cursing, but eventually we’ve got the 3D printer moving and extruding to our hearts content.
There’s a lingering bug with build ‘burping’s, but we do have to same something to work on for next weekend.
Max gave a demo of his quad-copter
Phi started work on a furnace
Adrian demod his ServoShield units
Jeremy gave a demonstration on how spontaneous symmetry breaking is done
Member's Projects -- 'Light Interrupted' by Adam Synnott
Introducing a new category here on the blog, Member’s Projects. We’d like to show off some of the things people are making, taking apart, remaking or whatever! Our first project is by Adam Synnott, and is called ‘Light Interrupted’. It was recently featured in ‘Serial Space’ in Chippendale.
Light Interrupted is a rear projected FTIR multi-touch display using a combination of Touch Designer and Max/MSP the screen. Adam is currently in development of a muti-touch 3d painter/modeller, an RSS fed globe, some reactive grass and a 3d fish tank.