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Arduino programming, Mega 2560 ADK

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AdeV:
Ahh, sometimes I get confused over which forum I'm posting on.....

So, to explain: The Lister CS "Start-o-matic" is  self-contained generator unit powered by a single-cylinder 6hp diesel engine driving a single-phase alternator/motor head. Typically, they were used as lighting plants for isolated farms, in the days when network electricity was rare/non existant, especially deep in the countryside. They were most prevalent in the 1940s-1960s, and are now much prized by people who want to do veg-oil or motor-oil powered "self sufficiency", due to their resilient nature and hypnotic low-speed running.

The Start-o-matic is connected to the house wiring via a control box. When a light is switched on, the control box senses it, and connects the alternator in "motor" mode. At the same time, it deactivates the compression release/fuel rack lever via a solenoid. The increasing RPMs (from driving the engine via the motor) eventually cause the diesel to start. Again, the control box senses this, and switches the motor circuit out, connecting the alternator circuit instead. Once the revs build up a mechanical governer kicks in to keep the voltage stable. The engine runs until the control box senses a no load condition (i.e. all lights switched off), this causes the "run" solenoid to turn off, and a spring pulls in the compression release/fuel rack closer. Thus, the engine shuts down. All 100% analogue, using bi-metallic strips, resistors, etc. It even had a fail-safe shutdown in case the engine didn't start.

This is all very clever, but I want to be able to do it via modern day electronics. There is no inverter, and the battery is a 12v car battery running a separate (car) starter. I can actuate the starter via relay, and I can spot the rpms rising above the cranking speed which allow me to disengage the starter once the diesel has fired (or give up after a certain number of cranks). I haven't yet figured out the actual stopping mechanism but I think a servo + spring will suffice, to push the rack/decompression unit into engagement. It will also allow it to disengage when starting.

So, the question is, if someone attempts to draw a load from the "mains", how to I detect this & kick the generator up? And how do I subsequently tell when no load is on, and therefore shut the generator down? I only need binary signals... there rest I can handle.

awemawson:
If I remember correctly, most Start-o-Matics used 24v. In the non running state the load circuit was biased with 24v DC, so when a load was switched on it causes a small current to flow which latches a relay on, which also drops the 24v dc bias. Relay then used to start machine.

The circuit is available on line somewhere as I wondered how they worked and 'googled' it a few years back

Andrew

Dawai:
Very cool.. Nothing i have ever saw or heard of before thou. (I really don't know everything, or claim to)..

I'd still pass the "house mains through a CT" and figure a way to read the current and "voltage present" for cases like we had a while back when the power went off, thou you'd want a switch to open it up so you didn't pump your electricity back into the power grid. (and burn it out)

make a post, post pictures.. I'm a old greybeard electrician, I will help if I can. I got boxes of obsolete junk laying about, but the import fees?? would kill ya.. I got this buddy in Ontario who thought I charged him for something, but it was Canadian import taxes.. and they price the industrial stuff like it is new.

awemawson:
Many many years ago (over thirty) I was looking at an old derelict water mill and it's attached cottage just over the River Tamar in Cornwall. Hadn't been lived in for many years, and was structurally questionable. I flicked a light switch in the cottage and to my amazement a few seconds later there was the chug chug of as diesel start up round the back. Went to have a look see and a Start-o-Matic in a shed round the back had fired up. How could the batteries have held a charge I thought? Well it turned out they were ex War Department NiFe cells ! Thinking about it the place wasn't that far from the Plymouth Naval Dockyard ....   mmm....

Place is now a trendy restaurant  :bang:

Andrew

Bluechip:
Andrew

Didn't that geezer E H Jeynes (?) do the odd article in ME about domestic generator plants ?

That 'Start-O-Matic' seems vaguely familiar for some reason, and I can't think of anywhere else I got it.  .... if, indeed I did ...  :scratch:

Dave BC

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