Here is a compiled version of the Linux kernel for the Raspberry Pi useful for those who have USB/Serial touchscreens of the 3M Microtouch or eloTouch variety.
Works with a freshly installed & fully updated Raspbian image.
I have tested this only with a 3M Microtouch EXII controller currently.
Simply overwrite the /lib folder with the new modules & overwrite the main kernel image in /boot to install.
[download id=”5568″]
Having two separate water tanks on nb Tanya Louise, with individual pumps, meant that monitoring water levels in tanks & keeping them topped up without emptying & having to reprime pumps every time was a hassle.
To this end I have designed & built this device, to monitor water usage from the individual tanks & automatically switch over when the tank in use nears empty, alerting the user in the process so the empty tanks can be refilled.
Based around an ATMega328, the unit reads a pair of sensors, fitted into the suction line of each pump from the tanks. The calculated flow is displayed on the 20×4 LCD, & logged to EEPROM, in case of power failure.
When the tank in use reaches a preset number of litres flowed, (currently hardcoded, but user input will be implemented soon), the pump is disabled & the other tank pump is enabled. This is also indicated on the display by the arrow to the left of the flow register. Tank switching is alerted by the built in beeper.
It is also possible to manually select a tank to use, & disable automatic operation.
Resetting the individual tank registers is done by a pair of pushbuttons, the total flow register is non-resettable, unless a hard reset is performed to clear the onboard EEPROM.
View of the main PCB is above, with the central Arduino Pro Mini module hosting the backend code. 12-24v power input, sensor input & 5v sensor power output is on the connectors on the left, while the pair of pump outputs is on the bottom right, switched by a pair of IRFZ44N logic-level MOSFETS. Onboard 5v power for the logic is provided by the LM7805 top right.
Code & PCB design is still under development, but I will most likely post the design files & Arduino sketch once some more polishing has been done.
After 13 months of very heavy use at various events, festivals & boat trips, the Li-Po battery pack at the heart of my portable power supply has died.
What initially started as one cell inflating spread to the other cells in the pack over a period of about 3 months, so I have completely replaced the pack with a larger unit.
The old pack was an 8.8Ah unit at 12.6v. By using smaller burst capacity cells, I have managed to squeeze in a total of 13.2Ah, still leaving space to spare for an extra 3 cell string along the top.
Here is the end of the battery pack, with all the cell interconnects. There are 3 2.2Ah cells in series to give the 12.6v terminal voltage, with 6 of those strings in parallel to give the total Ah rating.
A new charging circuit will be implemented to better handle the volatile chemistry of Li-Po cells, hopefully this will result in the pack lasting longer than a year!
The new higher capacity will hopefully help with power requirements at future events, still being charged during the day by a 24W solar panel, but at night will have to cope with charging two smartphones, two eCigs & running a few watts of LED lighting.
The trial-by-fire will be this year’s Download Festival in June, when I will be operating off-grid for 6 days.
More updates to come on improvements & failures!
The quickest project from inception to working PCB yet:
From inception to a working PCB took only 4 hours!
This is a miniature stereo audio amplifier, 0.5W per channel, that can be run from any voltage between 4-12v DC.
As usual, all the Eagle project files are available for download below & kits/bare PCBs will be available for sale for those that cannot etch boards.
Here is the circuit driving a pair of 3W 8Ω speakers from a line level audio source. The gain of this circuit is set at 50 with the components specified.
As can be seen from the schematic, this is a pair of single LM386 ICs for each channel.
Gain can be set by altering R3 & R4
[download id=”5566″]
Buy Kits Here £9.50:
[wp_cart_button name=”LM386 Stereo Audio Amplifier Kit” price=”9.50″]
Buy bare PCBs here £5:
[wp_cart_button name=”LM386 Stereo Audio Amplifier PCB” price=”5″]
PCBs are etched on FR4 laminate with 8oz copper with top component silkscreen.
To accompany the previous two posts about hydraulic generators & their components, here is the actual generator unit itself.
Rated at 8.5kVa 230v AC, this will providea mains supply while the narrowboat is away from her home mooring.
This unit will be attached to the side of the hull in the engine room on rubber vibration isolation mounts, behind the main hydraulic oil tank & is driven from the small gear pump attached to the back of the main propulsion hydraulic pump unit.
Operating pressure is 175 bar, 21L/m flow rate to achieve the 3,000RPM rotor speed for 50Hz mains frequency.
After passing my Foundation course on the 1st December, I have finally received my certificate & obtained my licence!
My new callsign is M6GCY. Time to get on the air!
While sourcing the main propulsion hydraulic system for nb Tanya Louise in the summer, we thought that it would be convenient to have an on board generator that didn’t require dragging off the boat & highly explosive petrol to operate.
As the hydraulics were already being fitted, we decided to add a hydraulically driven generator to solve this issue.
And this is where the problems began…
We were referred to Mike Webb of hydraulicgenerators.co.uk to supply the equipment required for this part of the project, this was to include the alternator itself, hydraulic motor to drive the alternator, the required adaptor plates to mate the motor to the generator head & a control valve block to regulate the oil flow & pressure to the motor.
After a phone call to Mike on 16-07-2013 to discuss our requirements, we settled on a system. I received the following E-Mail the next day from Mike:
Good morning, reference our conversation, Martin from BSP has given me details as to what he will be supplying, on that basis and in light of the special price I have offered, this is what I propose to supply,
1 off New 8kVa – 7kW Hydraulic driven generator 220v single phase 50hz c/w flow control valve, pressure relief valve and on/off solenoid valve, Martin did say that the engine idle is between 1000 and 1200 rpm and max speed is 3600 rpm, valves will be rated accordingly. I have the alternator and parts available now, in order for me to be able to offer this at a significantly discounted price of £ 1.200.00 nett, I will need to utilise the components I have in stock now, so I will need payment asap, delivery will be approx. 7 days, primarily due to the fact that the coupling is fabricated to suit, I can either deliver the unit to you when ready or BSP or hold onto it until everything else is in place. The alternator is a Meccalte S20W that I bought for another customer a few weeks ago, but he cancelled and I don’t have, at this time, anyone else interested in it, so either I do a deal with you at the above price or wait until someone else comes along and wants the unit.
With regards to installation, let me know if you need any help, but it would be best to install when the engine is being installed and the rest of the system hosed up, I assume BSP will be sorting this, in which case I’ll liase with Martin.
I trust that this meets with your approval and look forward to hearing from you.
At this point an order was placed with Mike, & the money transferred so he could begin building the unit for us. As can be seen from the E-Mail, a lead time of 7 days was stated.
After a few phone calls over the following month, firstly being told that the custom parts to mate the generator to the motor had not come back from the engineers, I sent another E-Mail to Mike on 10-09-2013, and got no reply.
Following another phone call, I was told that the generator had been shipped, however Mike would not give me any tracking details for the shipment, and would not initially tell me who it was shipped with.
Again the generator didn’t turn up.
More phone calls ensued & I was told at this point that the shipping company had been confused by the address given, shipped back to Mike. At this point I was informed that the shipping company had actually LOST it. Several more phone calls later I was promised that a replacement generator would now ship no later than 08-10-2013. A follow up E-Mail two days later also generated no reply.
At this point I was beginning to wonder if I would ever see the goods we had paid for, but finally a shipment arrived from Mike
~15-10-2013, over TWO MONTHS after our promised delivery date. However, even having been delivered, all was not well with the goods.
Above is the generator supplied. No mounting bracket, no integrated valve block, in short, nothing like what was described in Mike’s documentation & website. The original documentation is available here for reference: [download id=”5564″]
The valve block supplied was this:
Flow control: check.
Pressure relief: check.
Control solenoid valve: Gaping hole….
As can be seen, there is an open port on the side of the valve block. This is where the ON/OFF control solenoid valve is supposed to be located.
After several more unanswered E-Mails & phone calls, I had to get somewhat more forceful in my messages, as now Mike had begun outright lying about what was specified in the original order. In which that there was no solenoid valve required. So the following E-Mail was sent 21-10-2013:
Mike,
Having had a conversation with Martin, about him attempting to contact you regarding what you have supplied to us, I need this resolving ASAP now, as I am being held up by the fact that there is an open port on your valve block where the solenoid control valve is supposed to be located.
As it stands the valve block & therefore the generator you have supplied to us is useless for it’s intended purpose & I will be seeking legal advice on this matter if a resolution cannot be made this week, considering you have not replied to any E-Mail I have sent since the unit’s massively delayed arrived.
In your original correspondence it is certainly indicated that this valve was to be fitted, which was also Martin’s instruction to you.
I await your expedient response.
This threat of legal action actually spurred a response from Mike, who finally replied with the following on 25-10-2013:
Ben,
Sorry about all this, I have been away and down with a bug for the last week, I will sort this today and will have the required parts shipped to you on Monday for Tuesday delivery.
Regards
Mike
Another promise of a delivery date, so I waited a little longer, until the Friday of that week. Still no delivery. No surprise there then.
(I didn’t believe the story about illness either).
At this point I again attempted contact, but got nowhere, even with legal threats. So I’ve given up completely on this & been forced to source the parts elsewhere at extra cost.
This company is not the one to go to if you require a hydraulic generator unit for any application, as you’d be lucky to get any part of what you order on time, if at all.
Operations are run by an all out liar who seems to be happy to accept money but not ship the goods that had been paid for.
Mike having explained to me that the shipping company had lost a generator, and he would have to build me another one to replace it also does not make sense, as in the initial phone call & mail he stated that the Meccalte generator that we eventually received was a single unit that was specially ordered for another client, and the factory build date on the unit certainly gave away the fact that the generator head had been sat around for some considerable time before I came along & made a purchase.
Hopefully this post will get a high Google ranking, to ensure that anyone else who happens to be looking for a similar piece of equipment does not have the misfortune to trust this man.
We were referred to him on good faith & unfortunately in this case it did not go well.
Finally, after months of messing about with the original seller of the generator unit, (Mike Webb from hydraulicgenerators.co.uk, more to come about the nightmare I had dealing with this man), we have had to purchase a new hydraulic control valve for the genset, as the original unit supplied was missing parts.
Thanks to Martin Bullock from BSP Hydraulics for supplying this at short notice!
This unit contains a pressure relief valve, to set system operating pressure, a throttle/flow control valve to set generator motor speed & a solenoid controlled spool valve to control general oil flow to the generator. This last section effectively operates as an ON/OFF control.
System pressure will be ~175 Bar at 21 litres/minute.
More to come soon with the final assembly, hosing up & system commissioning.
Here is a simple 555 timer based flyback transformer driver, with the PCB designed by myself for some HV experiments. Above is the Eagle CAD board layout.
The 555 timer is in astable mode, generating a frequency from about 22kHz to 55kHz, depending on the position of the potentiometer. The variable frequency is to allow the circuit to be tuned to the resonant frequency of the flyback transformer in use.
This is switched through a pair of buffer transistors into a large STW45NM60 MOSFET, rated at 650v 45A.
Input power is 15-30v DC, as the oscillator circuit is fed from an independent LM7812 linear supply.
Provision is also made on the PCB for attaching a 12v fan to cool the MOSFET & linear regulator.
Board initially built, with the heatsink on the linear regulator fitted. I used a panel mount potentiometer in this case as I had no multiturn 47K pots in stock.
Bottom of the PCB. The main current carrying traces have been bulked up with copper wire to help carry the potentially high currents on the MOSFET while driving a large transformer.
This board was etched using the no-peel toner transfer method, using parchement paper as the transfer medium.
Main MOSFET now fitted with a surplus heatsink from an old switchmode power supply. A Fan could be fitted to the top of this sink to cope with higher power levels.
This is the gate drive waveform while a transformer is connected, the primary is causing some ringing on the oscillator. The waveform without an attached load is a much cleaner square wave.
I obtained a waveform of the flyback secondary output by capacitively coupling the oscilloscope probe through the insulation of the HT wire. The pulses of HV can be seen with the decaying ringing of the transformer between cycles.
Corona & arc discharges at 12v input voltage.
Download the Eagle schematic files here: [download id=”5561″]
Welded up now is the bracket for the main propulsion pump & the aux hydraulic pump to drive the 8.5kVa generator .
Here is the latest build & addition to the boat, in preparation for delivery of an 8kVa hydraulically driven generator unit – an automatic transfer switch.
Above can be seen the completed contactor unit, mounted in the engine bay.
This unit takes feeders from both the shore power socket & the generator unit & switches them independently through to the domestic 240v AC systems on board.
Contactor switching is done by a Datakom DKG-171 automatic generator controller.
Here are the contactors & isolators, before fitting to the wallbox. Power comes in one the left, through the large 25A isolating switches, before feeding to a pair of 30A contactors. The pair of outer relays next to the contactors are interlocks. These ensure that when one contactor is energized, the other is electrically locked out. Even if the interlock relay is manually operated with the orange flag visible on the top of the unit, they are wired to de-energize both contactors. This ensures that under no circumstances can both power sources be connected at the same time.
The generator controller requires a 68mmx68mm panel cutout for mounting. This was done in the main panel next to the electrical locker.
Here the contactor board has been fitted into the wallbox & the cable glands fitted before wiring.
The generator controller fitted & finally energized. The indicator LEDs on the front of the unit let the user know where power is currently being supplied from & which contactor is energized.
The original LM2577 based regulators I designed into my mobile battery pack turned out to be insufficient for requirements, therefore they have been replaced with higher capacity regulators.
The 12v regulator (left) is a muRata UQQ-12/8-Q12P-C SEPIC converter, providing a max of 8A at 12.1v DC. The 12v rail is also now independently switchable to save power when not in use.
The 5v regulator (right) is a Texas Instruments PTN78020WAZ switching regulator, rated at 6A. The pair of resistors on the back of the regulator set the output voltage to 5.1v.
Also a new addition is a pair of banana sockets & a 2.1mm DC jack, wired into the 12v DC bus, for powering various accessories.
Below the USB sockets is now a built in eCig charger, to save on USB ports while charging these devices.
These changes were made after much field testing of the unit at Cassiobury Park, Watford, for the IWA National Waterways Festival.
Here is an AVR powered optical tachometer design, that I adapted from the schematic found here.
I made a couple of changes to the circuit & designed a PCB & power supply module to be built in. The original design specified a surface mount IR LED/Photodiode pair, however my adjustment includes a larger IR reflectance sensor built onto the edge of the board, along with a Molex connector & a switch to select an externally mounted sensor instead of the onboard one.
There is also an onboard LM7805 based power supply, designed with a PCB mount PP3 battery box.
The power supply can also be protected by a 350mA polyfuse if desired. If this part isn’t fitted, then a pair of solder bridge pads are provided within the footprint for the fuse to short out the pads.
For more information on the basic design, please see the original post with the link at the top of the page.
Here is an archive of the firmware & the Eagle CAD files for the PCB & schematic design.
Here’s my latest project with the Pi: interfacing it with the Sparkfun Geiger counter & outputting the resulting data to a character LCD.
The geiger counter is interfaced with it’s USB port, with the random number generator firmware. A Python script reads from the serial port & every minute outputs CPM & µSv/h data to the display.
The Python code is a mash of a few different projects I found online, for different geiger counters & some of my own customisations & code to write the info to the display & convert CPM into µSv/h.
This also writes all the data into a file at /var/log/radlog.txt
The code for this is below:
[snippet id=”1149″]
As the cable supplied with the panel is far too short, inflexible & does not even allow the cable gland on the terminal box to form a seal, I have replaced it with some high quality twin core guitar cable, with silicone insulation.
The cable is removable from the panel tail by means of a screwlock two pin connector.
On another note, I have noticed a side effect of fitting a switchmode regulator to the panel: it seems to have formed an MPPT-type regulator setup, as even in low light conditions, when the bare panel is outputting 18.5v at 50mA short circuit, with the switching regulator I can get a useable 13.25v at ~170mA.
This effect is increased in full light, where I can obtain 4.5A short circuit current & ~1.8A at 13.25v output.
I have acquired a 24W monocrystalline solar panel to charge my portable battery pack while on the move. This panel will be able to charge all devices I carry on a regular basis with nothing but some sunlight!
Info on the panel itself. Rated at 24W with nominal 17.6v DC, 1.36A output.
I have installed a switching regulator in the back of the panel, where the connections would normally be wired straight to the array of cells. This regulates the voltage down to a constant 13.8v to provide more compatibility with 12v charging equipment. I have tested the output of the panel in late day sun, at 1.27A.
As the first USB hub I was using was certainly not stable – it would not enumerate between boots & to get it working again would require waiting around 12 hours before applying power, it has been replaced. This is a cheapie eBay USB hub, of the type shown below.
These hubs are fantastic for hobbyists, as the connections for power & data are broken out on the internal PCB into a very convenient row of pads, perfect for integration into many projects.
I now have two internal spare USB ports, for the inbuilt keyboard/mouse receiver & the GPS receiver I plan to integrate into the build.
These hubs are also made in 7-port versions, however I am not sure if these have the same kind of breakout board internally. As they have the same cable layout, I would assume so.
Here is a closeup of the back of the connectors, showing a couple of additions.
I have added a pair of 470µF capacitors across the power rails, to further smooth out the ripple in the switching power supply, as I was having noise issues on the display.
Also, there is a new reset button added between the main interface connectors, which will be wired into the pair of pads that the Raspberry Pi has to reset the CPU.
This can be used as a power switch in the event the Pi is powered down when not in use & also to reset the unit if it becomes unresponsive.
The final part for the battery pack has finally arrived, the PCM boards. These modules protect the cells by cutting off the power at overcharge, undercharge & overcurrent. Each cell is connected individually on the right, 12v power appears on the left connections. These modules also ensure that all the cells in the pack are balanced.
I have finally got round to designing the balancing circuitry for my ultracapacitor banks, which have a total voltage of 15v when fully charged. The 2600F capacitors have a max working voltage of 2.5v each, so to ensure reliable operation, balancing is required to make sure that each capacitor is charged fully.
The circuit above is a simple shunt regulator, which uses a 2.2v zener diode to regulate the voltage across the capacitor.
A 10W 1Ω resistor is connected to the BALLAST header, while the capacitor is connected across the INPUT. Once the voltage on the capacitor reaches 2.6v, the MOSFET begins to conduct, the 1Ω resistor limiting current to ~2.6A.
Each capacitor in the series string requires one of these connected across it.
Below is a link to the Eagle project archive for this. Includes schematic, board & gerber files.
[download id=”5555″]
My new rubidium frequency standard has arrived! I will be building a Stratum 1 Time Server with this, along with a GPS receiver. Check back for updates on this future project!
A few modifications were required to the SMPS modules to make the power rails stable enough to run the Pi & it’s monitor. Without these the rails were so noisy that instability was being caused.
I have replaced the 100µF output capacitors & replaced them with 35v 4700µF caps. This provides a much lower output ripple.
There are also heatsinks attached to the converter ICs to help spread the heat.
Progress is finally starting on the power supply unit for the Pi, fitted into the same case style as the Pi itself, this is an 8Ah Li-Poly battery pack with built in voltage regulation.
Here are the regulators, fixed to the top of the enclosure. These provide the 12v & 5v power rails for the Pi unit, at a max 3A per rail.
In the main body of the case the battery pack is fitted. This is made up of 4 3-cell Li-Poly RC battery packs, rated at 2Ah each. All wired in parallel this will provide a total of 8Ah at 12.6v when fully charged.
Here the regulators are powered up from a 13v supply for testing. I have discovered at full load these modules have very bad ripple, so I will be adding extra smoothing capacitors to the power rails to compensate for this.
Here are the connectors on the top of the unit, outputting the two power rails to the Pi & the DC barrel jack that will be used to charge the pack.
The hub for the external USB ports has been fitted here, with the two ports hardwired to the pads where once there were USB A sockets. This hub will also accommodate the wireless receiver for the mini keyboard & mouse, in the remaining port that will sit between the external USB ports.
In this gap between the ports is where the wireless receiver will sit for the keyboard & mouse, the pair of screws securing the external ports in the centre have been shortened to make more room.
For convenience, a pair of USB ports have been fitted to the wearable Pi, which open on the bottom of the unit. These will be hardwired into a 4-port USB hub which will also support the wireless adaptor for the mini-keyboard that is to be used with the device.
The two USB ports on the bottom of the casing.
The external connectors are also complete. The audio jack & second WiFi antenna port are fitted.
The audio is normally routed to the LCD display speaker, until a jack is plugged into the 3.5mm socket.
Here is the project I’m currently working on. A completely wearable computing platform based on the Raspberry Pi & the WiFi Pineapple.
Above can be seen the general overview of the current unit.
On the left:
On the right:
The WiFi, Pineapple & 3G all have external antenna connections for a better signal & the whole unit locks onto the belt with a pair of clips.
The Raspberry Pi is using the composite video output to the 7″ LCD I am using, running at a resolution of 640×480. This gives a decent amount of desktop space while retaining readability of the display.
The case itself is a Pelican 1050 hard case, with it’s rubber lining removed. The belt clips are also a custom addition.
Here are the connections to the main unit, on the left is the main power connector, supplying +5v & +12v DC. The plug on the right is an 8-pin connection that carries two channels of video, mono audio & +12v power to the display.
Currently the only antenna fitted is the 3G.
Closeup of the connections for power, audio & video. The toggle switch is redundant & will soon be replaced with a 3.5mm stereo jack for headphones, as an alternative to the mono audio built into the display.
Current state of test. Here the unit is running, provided with an internet connection through the Pineapple’s 3G radio, funneled into the Pi via it’s ethernet connection.
Running on a car reversing camera monitor at 640×480 resolution. This works fairly well for the size of the monitor & the text is still large enough to be readable.
Stay tuned for Part 2 where I will build the power supply unit.
