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Last Updated: January 17 2009 23:34

Telemetry & Control

RCC01 simple telemetry unit

RCC01 Remote Contact Closure
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I occasionally have to work on remote radio sites. Sometimes it would be handy to be able to switch things on/off on such sites and sometimes it would be nice to be able to monitor things like site alarm contacts remotely. There are products that will transmit contact closures like this over radio - but they seem to me to be a bit expensive for what they are. With this requirement in mind I designed my contact closure over text message unit.
This unit allows up to 8 potential free contact closures to be transmitted to 8 open collector outputs over any bearer that will pass a text message of at least 2 ASCII characters. I designed the units with Kenwood's DMS radios in mind, radios like the TK 880/780 and the newer TK8180/7180 provide for (amongst other things) a facility for transmitting text messages using the radios internal MSK modem. However although the unit was designed with Kenwood DMS in mind it should work with any 9600 baud RS232 interface that is able to send/receive a text message of at least 2 characters in length.

Some specifics

Each RCC01 unit provides 8 open collector outputs able to sink up to 500mA from a 50v source and 8 pull to ground TTL inputs.

  • The unit is also provided with a 9 way RS232 serial port configured as DCE.
  • A jumper wire is used to select program / run mode.
  • The RCC01 in a PCB approximately 100x60x20mm in size.
  • I/O is via a 25 way D female connector.
  • Details of the pinouts of this connector are here.
  • The operation of the unit is probably best understood by reading through the programming guide here.

The RCC01 is available as a fully populated unboxed PCB for £89.00 inc P&P. If paying by PayPal please add 3%+20p making a total of £91.87.
Discount is available for orders or 5 of more units, please contact me by the contact me form on this website for details



Diesel Generator Auto-Start Controller

I was recently asked to wire up a 6kva diesel generator to automatically start and switch online in the event of a mains failure. Another one of those easy jobs, just buy an auto-start controller and away we go I thought, but things are never that simple...
Firstly I noticed that auto-start controllers are rather expensive, up to £500 seems rather a lot to me for generating a few sequenced contact closures. Also the generator I was being asked to setup had no facility for wiring in an auto-start controller, manual start consists of turning a key to one position to warm up the glow-plugs, another to crank the starter and a third position to run, then once started the output load could be connected.
The result of this problem was my auto-start controller, it's basically a microprocessor controlled sequencer with 4 mains inputs and 6 relay outputs.

On failure of the mains supply it runs the required sequence:-
Glow-plug preheat, crank starter, run, connect load.
As you can see this is done with a simple single sided PCB pictured below. A read through the programming details will give a good understanding of the operation of the unit.

Outputs provided are all single pole change over relay contacts rated at 5 amps, you will normally be required to provide external contactors to accommodate the currents involved with larger generators.
Inputs are mains rated opto-isolated.

You should note that mains voltage is present on parts of the PCB and you should therefore take the required mains voltage precautions, if you are not qualified and comfortable with working on circuits at mains voltage you should not be doing this !!

Details of the specific inputs/outputs provided are here.

Note that you absolutely must ensure that the generator can never be connected to the supply from the electricity board,
this is best achieved using a contactor with 2 x normally open and 2 x normally closed contacts, this can be wired in a fail safe way.

The controller is available as a built tested PCB at a price of £96 in quantities of up to 5, for larger quantities a discount is available. As always if paying by PayPal add 3% + 20p making a total of £99.08.

The auto-start controller is equipped with 4 mains inputs and 6 relay outputs, so with custom software it could do all sorts of other jobs - if you have any specific requirements please let me know using the contact me form on this website.

G1SLE Generator Controller
Click image to view full size.

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