I recently came across a design for an Arduino controlled AD9850 DDS module, created by AD7C, so I figured I would release my Eagle CAD design for the PCB here.
It is a mainly single-sided layout, only a few links on the top side are needed so this is easy to etch with the toner transfer method.
My version uses an Arduino Pro Mini, as the modular format is much easier to work with than a bare ATMega 328.
RF output is via a SMA connector & has a built in amplifier to compensate for the low level generated by the DDS Module.
DDS VFO
Version 2 Update: Added reverse polarity protection, added power indicator LED, beefed up tracks around the DC Jack.
[download id=”5571″]
I was recently given some 4″ 7-Segment displays, Kingbright SC40-19EWA & of course, I needed to find a use for them.
I only have three, so a clock isn’t possible…
4″ 7-Segment Display
As these displays are common cathode, & have a ~9v forward voltage on the main segments, some driver circuity is required to run multiplexed from an Arduino.
Driver Transistors
Driver circuit built on Veroboard, PNP segment transistors on the left, cathode NPN transistors in the centre, level-shifting NPN array on the right.
Base Bias Resistor Network
Base bias resistors on the back of the board to bias the bases of the segment drive transistors correctly.
Display Rear
Board soldered into the pins of the displays, which have been multiplexed.
Schematic to come along with some Arduino code to run a room thermometer, with an LM35 sensor
To provide more run time with the conversion to petrol & spark ignition, I have also upgraded the on-board electronics supply to compensate for the extra ~650mA draw of the ignition module.
This modification is centred around a 3S Lithium-Polymer battery pack, providing a nominal 11.1v to a voltage regulator, which steps down this higher voltage to the ~6v required by the receiver & servo electronics.
Power RegulatorPower Regulator
The regulator, shown above, is a Texas Instruments PTN78060WAZ wide-input voltage adjustable regulator. This module has an exceptionally high efficiency of ~96% at it’s full output current of 3A. The output voltage is set by a precision resistor, soldered to the back of the module, in this case 6.5v. Standard RC connectors are used on the regulator to allow connection between the power switch & the radio receiver.
Receiver Box
Everything tucked away into place inside the receiver box. The 3S 1000mAh LiPo fits perfectly in the space where the original Ni-Mh hump pack was located.
The completely stable output voltage of the regulator over the discharge curve of the new battery gives a much more stable supply to the radio & ignition, so I should experience fewer dropouts. Plus the fact that the engine now relies on power from the receiver pack to run, it’s a built in fail safe – if the power dies to the receiver, the engine also cuts out.
While I was already well aware of the effects of petrol on silicone products – the stuff swells up & dissolves over a very short period of time, which makes it an unsuitable material for seals in a petrol fuel system.
Fuel Tank Cap Seal
I wasn’t aware the O-Ring on the fuel tank cap of the Savage is silicone, as can be seen in the image above it has swelled up to much larger than it’s original size. It’s supposed to sit in the groove on the cap & fit into the filler neck when closed.
This was only from a couple of hours of petrol exposure, now the seal is such an ill fit that the cap will not close properly.
The solution here is to replace the ring with a Viton O-Ring, 2.5mm cross section, 23mm ID. I assume the fuel tank is made of polypropylene – this should stand up fine to the new fuel.
Another concern was the O-Rings on the carburettor needles, however these seem to be made of a petrol-resistant material already & are showing no signs of deterioration after 24+ hours of fuel immersion.
The O-Rings that seal the engine backplate to the crankcase also seem to be working fine with the new fuel.
Another silicone part on the engine is the exhaust coupling, between the back of the cylinder & the silencer, I’m not aware of a suitable replacement as yet, although as it will mainly be exposed to the combustion products & not raw fuel, it may just survive the task.
Exhaust Coupling
The extra heat from burning petrol in one of these engines may also put a lot of stress on this component, if it eventually fails I may attempt a replacement with automotive hose – time will tell on this one.
Fuel Bottle
I’m also not sure of the plastic that standard fuel bottles are made from – their resin identification number is 7, so it could be any special plastic, but I’m guessing it’s Nylon.
However according to the spec sheet for Nylon, it’s chemically compatible with petrol – yet the plastic appears to be getting softer with exposure, so it may be a special blend designed specifically for glow fuel.
Besides these small glitches, the engine is running well on it’s newly assigned diet of petrol, I’m currently running an 18:1 mix of petrol to oil (250ml oil to 4.5L of petrol), this seems to be providing more than adequate lubrication. While it smokes like a chimney, plenty of unburned oil is making it out of the exhaust, so the engine’s internals should have a liberal coating.
I’m yet to actually run the model out in open space so I can start tuning the mixture, but bench tests are promising.
The engine now with it’s required ignition sensor, it is now mounted back on the chassis of the model. I have replaced the stock side exhaust with a rear silencer, so I could fit the ignition module in place next to the engine.
For the mounting, I fabricated a pair of brackets from 0.5mm aluminium, bent around the module & secured with the screws that attach the engine bed plate to the TVPs. The ignition HT lead can be routed up in front of the rear shock tower to clear all moving suspension parts, with the LT wiring tucked into the frame under the engine.
In this location the module is within the profile of the model chassis so it shouldn’t get hit by anything in service.
Rear Exhaust
New exhaust silencer fitted to the back of the model. This saves much space on the side of the model & allows the oily exhaust to be discharged away from the back wheel – no more mess to wipe up.
Kill Switch
The ignition switch fitted into the receiver box. This is wired into channel 3 of the TF-40 radio, allowing me to remotely kill the engine in case of emergency. I have fitted a 25v 1000µF capacitor to smooth out any power fluctuations from the ignition module.
The radio is running from a 11.1v 1Ah 3S LiPo pack connected to a voltage regulator to give a constant 6.5v for the electronics. I found this is much more reliable than the standard 5-cell Ni-MH hump packs.
Fuel Tank
The stock silicone fuel tubing has been replaced with Tygon tubing to withstand the conversion to petrol.
High Speed Needle
High speed needle tweaked to provide a basic running setting on petrol. This is set to ~1.5mm below flush with the needle housing.
Low Speed Needle
Low speed needle tweaked to provide a basic running setting on petrol. This is set to ~1.73mm from flush with the needle housing.
As petrol is a much higher energy density fuel, it requires much more air than the methanol glow fuel – ergo much leaner settings.
The settings listed should allow an engine to run – if nowhere near perfectly as they are still rather rich. It’s a good starting point for eventual tuning.
As there was no other online example of someone converting a glow/nitro car engine onto CDI ignition, I thought I would document the highlights here.
The engine is currently still running on glow fuel, but when the required fuel lines arrive I will be attempting the switch over to 2-Stroke petrol mix. This should definitely save on fuel costs.
The engine in this case is a HPI NitroStar F4.6 nitro engine, from a HPI Savage X monster truck.
F4.6 Engine
Above is the converted engine with it’s timing sensor. As The installation of this was pretty much standard, a complete strip down of the engine was required to allow the drilling & tapping of the two M3x0.5 holes to mount the sensor bracket to. The front crankshaft bearing has to be drifted out of the crankcase for this to be possible.
Ignition Hall Sensor
Detail of the ignition hall sensor. The bracket has to be modified to allow the sensor to face the magnet in the flywheel. Unlike on an Aero engine, where the magnet would be on the outside edge of the prop driver hub, in this case the hole was drilled in the face of the flywheel near the edge & the magnet pressed in. The Hall sensor is glued to the modified bracket with the leads bent to position the smaller face towards the back of the flywheel.
The clearance from the magnet to sensor is approx. 4mm.
Flywheel Magnet
Detail of the magnet pressed into the flywheel. A 3.9mm hole was drilled from the back face, approx 2mm from the edge, & the magnet pressed into place with gentle taps from a mallet & drift, as I had no vice to hand.
Initial timing was a little fiddly due to the flywheel only being held on with a nut & tapered sleeve, so a timing mark can be made inside the rear of the crankcase, across the crank throw & case to mark the 28 degree BTDC point, the flywheel is then adjusted to make the ignition fire at this point, before carefully tightening the flywheel retaining nut to ensure no relative movement occurs.
The slots in the sensor bracket allow several degrees of movement to fine adjust the timing point once this rough location has been achieved.
1/4″-32 Spark Plug
Definitely the tiniest spark plug I’ve ever seen, about an inch long. Some trouble may be encountered with this on some engines – the electrodes stick out about 2mm further into the combustion chamber than a standard glow plug does. This causes the ground electrode to hit the top of the piston crown. (This happens on the HPI NitroStar 3.5 engine). The addition of another copper washer under the plug before tightening should cure this problem.
RcExl CDI Ignition Module
Ignition module. Due to the depth of the plug in the heatsink head on these engines, I will have to modify the plug cap to straighten it out, as it will not fit in this configuration.
However, ignition modules are available from HobbyKing with straight plug caps, this makes modification unnecessary
The ignition & components used on this system were obtained from JustEngines.
OK, a few revisions have been made to the water management PCB, mainly to reduce the possibility of the brushed DC motors in the water pumps from causing the MCU to crash, with the other changes to the I/O connector positioning & finally upgrading the reverse blocking diode to a 10A capable version rather than 5A.
Here is the setup used to create the previous videos, the PiCE from Elson Designs makes the Pi water resistant, the only slight modification being to install a 2.5mm DC Barrel Jack into one of the grommet holes in the rear coupled with a custom DC-DC converter to power the setup.
A break from normal programming now to show a weekend canal cruise on the Macclesfield canal. Going from Marple to Poynton & returning later in the afternoon. This video was shot with the Raspberry Pi waterproofed with the PiCE From Elson Designs.
Just a short script to directly print files to the NCR 7197 Series printers under Linux as there is no direct driver. Certainly not finished or pretty, but functional.
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.
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.
Water Flow Sensor
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.
Main PCB
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.
New Pack
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.
Cell Interconnects
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.
The quickest project from inception to working PCB yet:
From inception to a working PCB took only 4 hours!
LM386 Amplifier
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.
In Operation
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.
Schematic
As can be seen from the schematic, this is a pair of single LM386 ICs for each channel.
I received this USB supply with a laser module from China that I purchased on eBay. I have heard of these nasty copies of Apple chargers going around, but I’d never received one this bad with a piece of Chinese electronics.
Label
Model No. A1265, so definitely an Apple clone. Apparently capable of +5v DC 1A output. Notice the American NEMA pins. This wouldn’t have been any use to me in the first instance since I am resident in the UK & our mains plugs are significantly different, not to mention significantly safer.
Manufacturer is marked as Flextronics.
Top Of Boards
Here is the charger disassembled. Inside the case these two boards are folded together, creating an alarmingly small isolation gap between the mains side of the supply & the 5v output. Both the low voltage output & the feedback loop for the supply runs over the 4-core ribbon cable.
The mains wiring from the board is as thin as hair, insulation included, so there is a big possibility of shorts all over the place from this part of the circuit alone.
Bottom Of Boards
Bottom of the PCB assemblies. Good luck finding any creepage distance here. There simply isn’t any at all. traces on the +350v DC rail on the mains side of the transformer are no more than 1mm away from the supposedly isolated low voltage side.
Plugging one of these devices into anything is just asking for electrocution.
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.
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 MONTHSafter our promised delivery date. However, even having been delivered, all was not well with the goods.
Generator Pallet
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″]
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!
Flow Control ModuleSolenoid Spool ValveControl Valve Block
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.
Initial Board
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.
PCB Traces
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.
MOSFET Heatsinked
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.
Gate Drive Waveform
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.
Flyback Secondary Waveform
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 DischargeArc Discharge
Corona & arc discharges at 12v input voltage.
Download the Eagle schematic files here: [download id=”5561″]
Here is a home laser hair removal unit, a Rio LAHS4. Shown above is the system overview, with the laser wand & the user controls.
Main PCB Top
Main base unit popped open reveals the main PCB, with the central processor, a PIC16F628A.
Main PCB Bottom
Other side of the PCB is mainly populated with power supply & filtering for the logic sections.
Wand PCB
Cracking open the laser wand reveals a stacked pair of PCBs, a main laser controller & the capacitive sensor PCB. This capacitive sensor connects to a pair of pins on the laser head & prevents operation if the unit is not held firmly against the skin.
Diode Module
Front of the laser diode module with the movable lens, on a pair of voice coil actuators. Very similar to the lens positioner used in any CD/DVD player pickup assembly.
The diode in this unit is an 808nm chip, with power in the 300-600mW range most likely.
Diode Module Rear
Rear of the diode module, with the connections to the diode itself & the voice coil positioner for the lens.
Wand PCB Top
Other side of the wand PCB, showing the capacitive sensor board on top of the main controller board. There is another CPU on the board here, which most likely communicates with the main processor in the base through a serial connection.
This is a passenger side airbag from a BMW vehicle. Here is the top of the device, with all the warning labels & information.
Folded Bag
Here the outer plastic wrap has been removed from the unit, showing the folded nylon fabric bag.
Frame
The base frame with the gas generator mounted.
Gas Generator
Gas generator with warning label. This is a two part generator, with a pair of independent cores inside.
Generator Core
One of the generator cores removed from the heavy steel shell of the gas generator. The layers of wire mesh on the outside act as a flame trap, releasing only the gas generated from the burning propellant inside.
Propellant
End cap removed from the core, showing the pellets of propellant & the many layers of mesh & fibreglass filter material. The explosive initiator is in the bottom of this unit. A spring under the end cap firmly holds the pellets against the initiator.
Initiator
Finally, here is the explosive initiator that is located in the bottom of the core under the propellant pellets. This consists of a primary explosive & an electric match, which can be seen below as the device is disassembled.
Here is a teardown of the Datakom DKG-171 generator transfer controller. Here is the front of the unit, with the pictogram of the system, the indicator LEDs & the generator test button.
Rear
The rear of the unit features the connection points for the mains, generator & generator control I/O.
PCB Rear
Rear of the PCB with the control relays. The two larger relays switch in the remote contactors to switch the mains supply over between the grid & the generator, while the smaller relay switches 12v power out to a terminal to automatically start the generator.
PCB Front
Front of the PCB with the control logic & main PIC microcontroller.
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.
Switching Unit
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.
Panel Cutout
The generator controller requires a 68mmx68mm panel cutout for mounting. This was done in the main panel next to the electrical locker.
Box Fitted
Here the contactor board has been fitted into the wallbox & the cable glands fitted before wiring.
DKG-171System Online
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.
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