These speakers are available free from Pringles, with two packs bought. Normally running on 3x AAA cells, I have made modifications to include a high capacity Li-Ion battery & USB charging.
18650 Battery
New battery is 3x 18650 Li-Ion cells in parallel, providing ~6600mAh of capacity. These are hot glued inside the top of the tube under the speaker, with the charging & cell protection logic.
The battery charging logic is salvaged from an old USB eCig charger, these are single cell lithium chargers in a small form factor ideal for other uses. Charging current is ~450mA.
Amplifier Board
The cells are connected to the same points as the original AAA cells, with the other pair of wires going into the top of the device to connect to the MicroUSB charging port.
The amplifier in this is a LM4871 3W Mono amplifier IC, connected to a 6Ω 1W speaker.
The other IC on the board is unidentifiable, but provides the flashing LED function to the beat of the music.
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.
New Additions
Below the USB sockets is now a built in eCig charger, to save on USB ports while charging these devices.
IWA National Festival 2013
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.
Schematic
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
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 Panel
Info on the panel itself. Rated at 24W with nominal 17.6v DC, 1.36A output.
Regulator
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.
Here is a quick look inside the FE-5060A Rubidium Frequency Standard. Above you can see the entire physics package, with the rubidium lamp housing on the right hand side. The ribbon cable running into the resonator cavity has the power & signal traces for the internal heater, temperaturesensor & Helmholtz coil.
Lamp End
Here is the lamp end of the physics package, with the voltageregulator & RFdriver for the lamp. The FETs soldered to the back of the housing are being used as heaters to maintain a constant temperature on the lamp in operation.
The temperaturesensor can be seen between the two FETs, with a single copper wire running around the housing to connect to it.
Main frequency synth board. This contains the RS-232 interface & the AD9830A from Analog Devices. This IC is a direct digital synthesizer & waveform generator.
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.
Breakout Hub
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.
Connector Panel
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.
PCB
Below is a link to the Eagle project archive for this. Includes schematic, board & gerber files.
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.
Regulator Boards
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.
Battery Pack
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.
Powered Up
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.
I/O
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.
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.
USBs
The two USB ports on the bottom of the casing.
External Connections
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:
Alfa AWUS036NHA USB High Power WiFi Network Interface
512MB Model B Raspberry Pi, 16GB SD card, running Raspbian & LXDE Desktop. Overclocked to 1GHz.
On the right:
WiFi Pineapple router board
USB 3G card.
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.
Connections
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.
Connectors
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.
Test Run
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.
Pi Goodness!
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.
This is a late 90’s business timeclock, used for maintaining records of staff working times, by printing the time when used on a sheet of card.
Front Internal
Here is the top cover removed, which is normally locked in place to stop tampering. The unit is programmed with the 3 buttons & the row of DIP switches along the top edge.
Instructions
Closeup of the settings panel, with all the various DIP switch options.
CPU & Display
Cover plate removed from the top, showing the LCD & CPU board, the backup battery normally fits behind this. The CPU is a 4-bit microcontroller from NEC, with built in LCD driver.
PSU & Drivers
Power Supply & prinhead drivers. This board is fitted with several NPN Darlington transistor arrays for driving the dox matrix printhead.
Printhead
Printhead assembly itself. The print ribbon fits over the top of the head & over the pins at the bottom. The drive hammers & solenoids are housed in the circular top of the unit.
Printhead Bottom
Bottom of the print head showing the row of impact pins used to create the printout.
Bottom of the solenoid assembly with the ribbon cable for power. There are 9 solenoids, to operate the 9 pins in the head.
Return Spring
Top layer of the printhead assembly, showing the leaf spring used to hold the hammers in the correct positions.
Hammers
Hammer assembly. The fingers on the ends of the arms push on the pins to strike through the ribbon onto the card.
Solenoids
The ring of solenoids at the centre of the assembly. These are driven with 3A darlington power arrays on the PSU board.
Gearbox Internals
There is only a single drive motor in the entire unit, that both clamps the card for printing & moves the printhead laterally across the card. Through a rack & pinion this also advances the ribbon with each print.
In preparation for my laser scanner project, I have modified my existing 445nm laser to accept a TTL blanking input. The laser driver is already enabled for this & just required an extra connection to interface with my laser scanner showboard. I have used an 8-pin connection to allow the same cable & interface to be used with an RGB laser system, when it arrives. The signals are as follows, from top centre, anti-clockwise:
Pin 1: +12v Power
Pin 2: Blue TTL
Pin3: GND
Pin 4: Green TTL
Pin 5: GND
Pin 6: Red TTL
Pin 7: GND
Centre: Power GND
Custom TTL Cable
Here is the custom 8 core cable, which connects to the laser scanner show board. This cable allows the laser to be used for projection while still retaining the portable function & the keylock arming switch. When plugged in the cable bypasses the keyswitch & provides 12v DC direct to the laser driver.
Having had a He-Ne laser tube for a while & the required power supply, it was time to mount the tube in a more sturdy manner. Above the tube is mounted with a pair of 32mm Terry Clips, with the power leads passing through the plastic top. The ballast resistor is built into the silicone rubber on the anode end of the tube. (Right).
Output power is about 1mW for this tube, which came from a supermarket barcode scanner from the 90’s. The tube is dated August 1993 & is manufactured by Aerotech.
Internals
Inside the box is the usual 2.2Ah 12v Li-Po battery pack & the brick type He-Ne laser supply. The small circuit in the centre is a switchmode converter that drops the 12v from the battery pack to the 5v required for the laser supply.
Here is a followup from the 1.5W laser module post.
The module has been fitted into a housing, with a 2.2Ah Li-Poly battery pack. Charging is accomplished with an external 12.6v DC power supply.
Above can be seen the pair of switches on the top, the keyswitch must be enabled for the laser to fire.
Armed
When armed, the ring around the push button illuminates blue, as a warning that the unit is armed.
Switch Wiring
Inside the unit. The Li-Poly battery pack is at the bottom, with it’s protection & charging circuitry on the top. The switches are wired in series, with the LED connected to illuminate when the keyswitch is turned to the ON position.
Laser Driver
The push button applies power to the laser driver module, which regulates the input power to safely drive the semiconductor laser in the aluminium heatsink housing.
Here are a few details of a valve amplifier I am building, using the valve related parts from a 1960’s reel to reel tape recorder.
This amplifier is based on an a Mullard ECL82 triode/pentode valve, with an EM84 magic eye tube for level indication.
Beginnings Of The Amplifier
Here the first components are being soldered to the tags on the valve holder, there are so few components that a PCB is not required, everything can be rats-nested onto the valve holders.
Progress
Progressing with the amplifier section componentry, all resistors are either 1/2W or 2W.
Valve Sockets Fitted
Here the valve holders have been fitted, along with the output transformer, DC smoothing capacitor & the filament wiring, into the top of the plastic housing. At this point all the components that complete the amplifier section are soldered to the bottom of the right hand valve holder.
Wiring
Starting the wiring between the valves & the power supply components. The volume control pot is fitted between the valve holders.
Valves Test Fit
The valves here are test fitted into their sockets, the aluminium can at the back is a triple 32uF 250v electrolytic capacitor for smoothing the B+ rail.
Amplifier Section First Test
First test of the amplifier, with the speaker from the 1960’s tape recorder from which the valves came from. the 200v DC B+ supply & the 6.3v AC filament supply is derived from the mains transformer in the background.
Magic Eye Tube Added
Here the magic eye tube has been fitted & is getting it’s initial tuning to the amplifier section. This requires selecting combinations of anode & grid resistors to set the gap between the bars while at no signal & picking a coupling RC network to give the desired response curve.
Final Test
Here both valves are fitted & the unit is sitting on it’s case for final audio testing. the cathodes of the ECL82 can be clearly seen glowing dull red here.
In the final section, I will build a SMPS power supply into the unit to allow it to be powered from a single 12v DC power supply.
This is a fan cooled 445nm laser module, which emits in the blue part of the spectrum.
Fan cooled & with TTL control built in, this is the beginning of a new laser projector.
Here’s the regulator hooked up with test clips, on the right is the supply from the ultracapacitor bank, while on the left is the output, feeding a 2.3A brushless fan as a test load.
These regulators do get warm, even with no load, with a 2.3A load on the output, the temperature stays warm to the touch.
Just a very quick post with some images of an industrial safe combination lock.
Tumblers Aligned
Here the tumblers are lined up to allow the lock to open.
Bolt Locked
The locking bar has dropped into the slots in the tumbler plates & engaged with the cam.
Bolt Unlocked
Rotating the cam pulls the bolt into the lock, allowing the door to open.
Unlocked
The dial screws into the cam plate to allow the mechanism to be operated.
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