Recent content by MikeAusC

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  1. M

    SILICA GEL TREATMENT-OVEN THERAPY?

    I dry small Silica Gel sachets, as used with medicines, by storing in a jar over Calcium Chloride pellets - it's slow but no heat is needed. You can get cheap Calcium Chloride pellets at the supermarket, by looking for refills for dehumidiers for use in cupboards e.g. Damp Rid. Calcium...
  2. M

    DIY USB powersource

    At this low power level a DC-DC converter is overkill. The interference from the converter AC is also likely to cause interference. The simplest way is to use two 1N4148 diodes in series as a 1.4 volt Zener diode. The + side of the diode connect to AAA negative and to USB in Gnd. Connect a 100...
  3. M

    Capacitor charging indicator

    Put the circuit diagram into image-editing software, turn the image upside down, enter that circuit into your modelling software . . . . . . or just use the answers I provided in Post #8.
  4. M

    Help with LED drivers

    Yes. Firstly adjust the output voltage at open circuit to 34 v and set the current to minimum.
  5. M

    Help with LED drivers

    10 in series means you'll want 32 volts at at 2500ma - that's 80watts - so it's within the power ratings. As it's a boost converter, it'll work with the input less than 32 volts. The power to an LED is controlled most easily by setting the current going through it, so set the current to 2500mA...
  6. M

    Led vf vs. direct drive LiFePO4

    - and that's why I won't use Direct Drive !
  7. M

    How to stay above the forward voltage

    No, Statement 2 is explaining the laws of physics.
  8. M

    How to stay above the forward voltage

    You can't regulate both voltage and current to an LED - you set the current, the LED will determine the voltage drop across it . . . . you set the voltage, the LED will determine how much current flows through it.
  9. M

    Copper Oxidation & Electrical Conductivity

    Copper has double the thermal conductivity of Aluminium - but only by volume. When you compare by weight, copper's advantage is lost.
  10. M

    Battery Selection for Brief Short-Circuit Pulse

    LiPO batteries for radiocontrolled models are designed to consistently discharge at 30C - i.e. a 1 amphour battery can discharge at 30 amps - and they're so cheap now. Just don't discharge below 2.5 volts when at rest. Or use a Supercapacitor e.g. 5 Farad at 2.7 volts and charge it from a...
  11. M

    Copper Oxidation & Electrical Conductivity

    Use Lanolin Grease or oil - available at any big hardware store. It's one of the most waterproof greases available. It won't cause a contact problem - it's easily displaced at metal-to-metal contact points. I use it to prevent corrosion at car battery terminals. Copper has been used forever in...
  12. M

    DIY LED Driver

    Driving a single white LED using a Linear driver is very inefficient - you'll be wasting 3/4 of your power in the Driver/resistor. Switchmode drivers are are usually over 80% efficent and cost about $5 from dealextreme. Driving 3 white LEDs in series with just a resistor from 12 is verty...
  13. M

    Embedding RGB Leds in Table - Need recommendations/Info/Help/Cats

    For a quick no-programming and cheap solution, look in the Discount shops for Christmas lights and build those into the table.
  14. M

    One MOSFET versus two MOSFETs in a protection circuit?

    MOSFETs can only control current flow in one direction. They have an inherent diode in reverse-parallel to the Drain-Source switch path. This means that if you use one MOSFET to switch off the circuit when voltage drops below a limit, it can never stop over-charging because current will always...
  15. M

    Capacitor charging indicator

    No, you've got it wrong. R1 is 2.7k and R2 is 10k. So V2 is 0.6 x 10 /12.7 = 0.47v. So when the Shunt resistor has 0.13 v across it, it will add to the 0.47v, giving 0.6 v across the Base-Emitter of the transistor.
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