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Member since Dec 2013 • Last active May 2015
  • 11 conversations

Most recent activity

  • in Projects
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    My Pico arrived through the letter box this morning. Good work Gordon with the delivery of the Kickstarter project.

    This little project will now be alive again to roll into its second iteration after a great deal of learning from the first!

    @LawrenceG I have sent you a PM.

  • in General
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    I have some from Farnell (1850226). Imagine that is complete overkill, the ebay stuff is probably just as good.

  • in Projects
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    There has been slow progress with the project.

    However new year and its my intention to make further progress with this project. I want to design the next version which is to be compatible with the new Pico.

    Would it be possible for you to create an Eagle part for the new Pico so I am able to get a head start for when it arrives?

  • in General
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    You could use 12vDC to power everything.

    Obviously you would then need a relay with a 12vDC relay coil if you are still using a relay.

  • in General
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    If you overload a supply the voltage will start to fall. The reason the Espruino resets is that the in-rush current for the relay coil is pulling down your supply voltage.
    There are usually datasheets for relays with this information on.

    I would suggest working back from what you are switching.

    • What device on the relay are you switching? i.e. boiler, heater, light etc.
    • The voltage and current are you switching with the relay? i.e. the device load.
    • How long are you switching the device on for?

    The ULN2003 will switch up to 500mA. The relay you are using has contacts rated at something like 10A @ given voltages. As you can see this is a big difference.

    Bi-stable relays or 'flip flop' relays switch the contact state each time you energise the coil. Again it depends what you are switching. If the power fails you need to make sure it fails to a safe state!

  • in General
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    @lavamantis - It's nice to see you progressing with your project.

    Depending on your specific project requirements it might be worth investigating alternative methods of switching the DC load. Using a standard relay might not be the most efficient.

    If it has to be a relay, look into using a bi-stable relay. This only requires a quick pulse to change the contact state.

  • in Projects
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    Just a quick update.

    ALWAYS USE PROTECTION... I should have known better really but I got lazy and there were actual flames, but no injuries!!

    Connected the 24VAC GND to the DC GND and it really does not like it when using a bridge rectifier.

    After a small moment of panic and further investigation, it appears the only damage was the bridge rectifier, primary side rectifier PCB tracks disintegrated and the two tiny jumper wires I was using connected directly to the 24VAC transformer were the items that caught fire.
    Most importantly the Espruino is still okay, its still relatively isolated being powered via USB at the moment.

    Next week I will replace the bridge rectifier with half wave rectification, use some protection on the secondary side of the transformer, make sure the wires are suitably sized and try again. In theory this should do the trick.

    I have finished adding on all the input connectors and hooked up a thermistor bead on each input. They at least seem to be working just fine now.

    Need to track down a 4-20mA sensor to test. I'm sure I had one kicking around!

  • in Interfacing
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    You should be fine with the 6v.

  • in Projects
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    I'm pretty pleased with it too considering its only the second PCB I have designed!

    Analog outputs are generally as below.