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Camping Support Trolley – Some Build Progress

Since I do festivals every year, along with a couple of other camping trips if the weather is good enough, I’ve been taking equipment with me for years in flight cases to make things more comfortable. Things like a large battery to power lights & device charging, an old Eberspacher diesel heater for the times when the weather isn’t great, and an inverter to run the pumps built into airbeds.

Red Diesel / Heating Oil is my fuel of choice for camping purposes, as it’s about the safest fuel around, unlike Butane/LPG it is not explosive, will not burn very readily unless it’s atomized properly & it’s very cheap. Paraffin is an alternative fuel, but it’s expensive in the UK, at about Ā£12 per 5L.
The Hexamine-based tablet fuels the UK festivals promote is nasty stuff, and the resulting combustion products are nastier still. (Things like Hydrogen Cyanide, Formaldehyde, Ammonia, NOX). They also leave a sticky black grok on every cooking pot that’s damn near impossible to remove. Meths / Trangia stoves are perfectly usable, but the flame is totally invisible, and the flammability of alcohol has always made me nervous when you’ve got a small pot of the stuff boiling while it’s in operation in the middle of a campsite filled with sloshed festival goers. A single well-placed kick could start a massive fire.

Previous System
Previous System

Over the years the gear has evolved and grown in size, so I decided building everything into one unit on wheels would be the best way forward. I’ve been working on this for some time, so it’s time to get some of the details on the blog! Above you can see the system used for last year’s camping, the heater is separate, with a 25L drum of heating oil, the battery is underneath the flight case containing all the power components, and it’s currently charging All The Things.

Overview
Overview

Above is the new unit almost finished, the bottom frame is a standard eBay-grade 4-wheel trolley with a few modifications of my own, with a new top box built from 12mm hardwood marine plywood. This top is secured in place with coach bolts through the 25mm angle iron of the trolley base. The essential carbon monoxide detector is fitted at the corner.

Internal View
Internal View

The inside gets a bit busy with everything crammed in. The large Yuasa 200Ah lead-acid battery is at the far end, with it’s isolation switch. Right in the middle is the Eberspacher heater with it’s hot air ducting. I’ve fitted my usual 12/24v dual voltage system here, with the 24v rail generated from a large 1200W DC-DC converter.

Heater Vent
Heater Vent

The hot air duct for the heater is fed out through a standard vent in the front. Very handy for drying out after a wet day.

Main Bus Bars & Solar Controller
Main Bus Bars & Solar Controller

Here’s a closeup of the distribution bus bars, with both negative rails tied together in the centre to keep the positives as far away from each other as possible, to reduce the possibility of a short circuit between the two when working on the wiring. The EpEver Tracer 4210A MPPT Solar Charge Controller is on the left, tucked into the corner. This controller implements the main circuit protection for the battery, having a 40A limit. Individual circuits are separately fused where required. Solar input on this unit is going to be initially provided by a pair of 100W flexible panels in series for a 48v solar bus, the flexible panels are essential here as most of the festivals I attend do not allow glass of any kind onsite, not to mention the weight of rigid panels is a pain.

DC Output Sockets
DC Output Sockets

I’ve stuck with the 3-pin XLR plugs for power in this design, giving both the 12v rail, 24v rail & ground.

Inverter Outputs
Inverter Outputs

Tucked under the DC outputs are a pair of panel sockets for the 600W inverter. This cheapo Maplin unit is only usually used to pump up air beds, so I’m not expecting anyone to pull anything near max output, but a warning label always helps.

Power Socket Wiring
Power Socket Wiring

Behind the front panel is the hardwiring for the power sockets. The DC jacks are connected together using 2mm solid copper wire, bent into bus bars.The mains wiring underneath is a simple radial circuit straight from the inverter. The large cylinder on the left is a hydraulic pump from a BMW Z3, which runs a hydraulic cylinder for lifting the lid of the top box, used simply because I had one in the box of junk.

Fuel Pump
Fuel Pump

External fuelling is dealt with by a small gear pump, this is used to fuel up the Optimus Stove & Petromax Lantern. This is in fact a car windscreen wash pump, but it has coped well with pumping hydrocarbons, it currently has a small leak on the hose connections, but the seals are still entirely intact.

Remote Relays
Remote Relays

There’s a small remote relay module here, for switching the DC output for lighting & the heater from afar. Very useful when it’s dark, since there’s no need to fumble around looking for a light switch. A car-style fob on my keyring instead.

Heater Timer
Heater Timer

Since the Eberspacher 701 controller I have is an ex-BT version, it’s very limited in it’s on time, a separate timeswitch is fitted to control the heater automatically. Being able to return to a nice warm tent is always a bonus.
Just to the left can be seen the top ball joint for the hydraulic cylinder that lifts the top of the box.

Battery Charger
Battery Charger

The final large component is the battery charger. This unit will maintain the battery when the trolley isn’t being used.

Router Motherboard
Router Motherboard

On the left side is the old Atom motherbaord used to provide a 4G router system. This unit gets it’s internet feed from a UMTS dongle & provides a local WiFi network for high speed connectivity. The bottom of the hydraulic cylinder is visible in the bottom right corner.

Fuel Tank Completed
Fuel Tank Completed

Since the Eberspacher obviously needs fuel, a tank was required. In previous years I’ve used jerry cans for this purpose, but this trolley is supposed to have everything onboard, for less setup time. The tank is constructed from 3mm steel plate, MIG welded together at the seams to create a ~40L capacity. The filler neck is an eBay purchase in Stainless Steel. No photos of the tank being welded together, as I was aiming to beat sunset & it’s very difficult to operate a camera with welding gauntlets on šŸ˜‰

The tank is the same width as the trolley frame, so some modification was required, having the wheels welded directly to the sides of the tank. This makes the track wider at the rear, increasing stability.

Fuel Dip Tubes
Fuel Dip Tubes

A quick view inside the tank through the level sender port shows the copper dip tubes for fuel supply to the heater, and an external fuel hose for my other fuel-powered camping gear. These tubes stop about 10mm from the bottom of the tank to stop any moisture or dirt from being drawn into the pumps.

Fuel Feeds & Level Sender Port
Fuel Feeds & Level Sender Port

The top of the tank is drilled for the fuel fittings & the level sender and has already been painted here. The 1mm base plate has yet to be painted.

Level Sender Installed
Level Sender Installed

Touching up the paint & fitting the sender is the last job for this part. The mesh bottom of the trolley has been replaced by a 1mm steel sheet to support the other parts, mainly the heater. Fuel lines are run in polyurethane tubing to the fuel pumps.

All the instruments & controls are on a single panel, with the Eberspacher thermostat, external fuelling port & pump switch, inverter control, the solar controller monitor panel, cover buttons, router controls, compressed air & fuel gauges.

Panel Wiring
Panel Wiring

As is usual behind instrument panels, there’s a rat’s nest of wiring. There’s still the pressure gauge to connect up for the compressed air system, and the nut on one of the router buttons is such a tight fit I’ve not managed to get it into place yet.

Eberspacher Fuel Pump
Eberspacher Fuel Pump

The support components for the Eberspacher heater are mounted underneath the baseplate, with the fuel dosing pump secured to a rail with a pair of cable ties, and some foam tape around to isolate the constant clicking noise these pumps create in operation. The large black cylinder is the combustion air intake silencer, with the stainless steel exhaust pipe to the left of that. Silencing these heaters is essential – they sound like a jet engine without anything to deaden the noise. Most of this is generated from the side-channel blower used in the burner.

Eberspacher Exhaust
Eberspacher Exhaust

Bolted to the underside are a pair of exhaust silencers, one is an Eberspacher brand, the other is Webasto, since the latter type are better at reducing the exhaust noise. Connections are sealed with commerical exhaust assembly paste, the usual clamps supplied do not do a good enough job of stopping exhaust leaks.

Next update to come when I get the parts in for the air compressor system.

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Brother PT-E300 Industrial Label Machine Teardown

Tape Installed
Tape Installed

Here a tape is installed in the printer. This unit can handle tape widths up to 18mm. The pinch rollers are operated by the white lever at the top of the image, which engages with the back cover.

Li-Ion Battery
Li-Ion Battery

This printer is supplied with a rechargeable battery pack, but AA cells can be used as well. Some of the AA battery terminals can be seen above the battery.

Battery Specs
Battery Specs

Pretty standard fare for a 2-cell lithium pack. The charging circuitry doesn’t appear to charge it to full voltage though, most likely to get the most life from the pack.

Cartridge Slot
Cartridge Slot

With the cartridge removed, the printer components can be seen. As these cartridges have in effect two rolls, one fro the ribbon & one for the actual label, there are two drive points.

Pinch Rollers & Print Head
Pinch Rollers & Print Head

The thermal print head is hidden on the other side of the steel heatsink, while the pinch rollers are on the top right. The plastic piece above the print head heatsink has a matrix of switches that engage with holes in the top of the label cartridge, this is how the machine knows what size of ribbon is fitted.

Mainboard
Mainboard

Most of the internal space is taken up by the main board, with the microprocessor & it’s program flash ROM top & centre.

Charger Input
Charger Input

The charger input is located on the keyboard PCB just under the mainboard, which is centre negative, as opposed to 99% of other devices using centre positive, the bastards.

LCD Module
LCD Module

The dot-matrix LCD is attached to the mainboard with a short flex cable, and from the few connections, this is probably SPI or IĀ²C.

Print Mech Drive
Print Mech Drive

The printer itself is driven by a simple DC motor, speed is regulated by a pair of photo-interrupters forming an encoder on the second gear in the train.

Battery Holder Connections
Battery Holder Connections

The back case has the battery connections for both the lithium pack & the AA cells, the lithium pack has a 3rd connection, probably for temperature sensing.

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Maplin A24GU Wireless Audio Module Teardown

Transmitter
Transmitter

This is a pair of modules that Maplin was selling some time back, to send stereo audio over a 2.4GHz radio link. The transmitter identifies as a USB sound card, I’ve personally used these units to transmit audio about 60ft. The transmitter, above, has a single button for pairing with the receiver below.

Receiver
Receiver

The receiver unit has a large external antenna, a link status LED & volume buttons, these directly control the volume level on the host PC via the sound card drivers.

Receiver PCB Top
Receiver PCB Top

Popping the case open on the receiver reveals a large PCB, holding the chipset, along with the audio output jacks & Mini-USB power input. The antenna Coax is soldered to the PCB.

Receiver PCB Bottom
Receiver PCB Bottom

The top of the board has the control buttons, and the status LED.

Receiver Chipset
Receiver Chipset

The chipset used here is a Nordic Semiconductor nRF20Z01 2.4GHz Stereo Audio Streamer, there’s a small microcontroller which does all the register magic on the RF transceiver. The RF chain is at the top of the photo, audio outputs on the top left, and the micro USB power input & voltage regulators at bottom left.

Transmitter PCB Top
Transmitter PCB Top

The transmitter PCB has a Sonix USB Audio Codec, to interface with the host PC. This is then fed into another Nordic Semi part on the opposite side of the board:

Transmitter PCB Bottom
Transmitter PCB Bottom

The bottom of the transmitter has the RF section, and another small control microcontroller.