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  1. duke37

    Is there something to use to flash 2 led lights quickly?

    I am also in the UK. If you look on the Maplin website, it will give details of the range of voltages which can be used. I am not looking again but I think they run on 5 to 12V or so, Did you try the Maplin website?
  2. duke37

    Transformer from china

    The label says 16.5VDC so I think this may ba a power supply not a transformer. What does it do? 5W can hardly drive a fridge freezer.
  3. duke37

    Is there something to use to flash 2 led lights quickly?

    You will need a plug in timer and a plug in low voltage power supply. Maplins have flashing leds in UK. Try searching 'flashing' on their website. Examples are UK30H, UK37S, UK38R, UK42V. These are red leds, they do other colours also. They are obviously not rare beasts and may be found...
  4. duke37

    Electronics Beginner; What equiptment to buy?

    I would start simple and work up. It all depends on what you want to do. If you wish to repair tube radios, then an isolating transformer is required. If you wish to make printed cicuits then suitable laboratory equipment is required. Start with digital and analogue meters, get cheap ones as...
  5. duke37

    Component orientation.

    Why replace the components if they are working? The signal to your speakers is AC, the current goes one way then the other so at some time what is 'upsteam' becomes' downsteam thus the components can be connected either way round. The components should have the same specifications e.g...
  6. duke37

    Program a pulsating/reversing

    Things tend to stay the same because the laws of physics do not change. Motors are better than solenoids since they do not have to stop a mass and restart it each time. To get vibration such as a fly or bee does it is necessary to tune the vibrating weight with a spring so that the energy...
  7. duke37

    4-20mA repeater output!

    As I pointed out earlier and as Joey says, you do not need an op-amp and you certainly do not need R7. The current source is intended to run into something approaching a short circuit and adding R7 will not help. An accurate voltage source should feed a very high resistance. An accurate...
  8. duke37

    help with my atmega16 ADC conversion

    I was involved with a large data logger some time ago which had a similar problem. A large capacitor was charged up and the voltage measured as it slowly discharged. The measured value came down in steps with a resolution of about 8 bits. The problem was digital interference into the...
  9. duke37

    4-20mA repeater output!

    This is how I envisage the thing should work. Diagram A shows the 4 to 20mA signal coming from an external source. No amp is needed, the voltage across the resistor will be 40 to 200mV and would go straight to the pic. If the transducer needs to be in the lower part of the loop then the amp...
  10. duke37

    4-20mA repeater output!

    Please give details of what is conncted to TP1 and TP2. Where is the load resistor? Your diagram shows 4-20mA output from TP2 but there is no output from here, TP1 and TP2 are both inputs.
  11. duke37

    Who built the Sun Tracker?

    Rather than rebuilding it wrong for the Nth time or re-installing a faulty component, I would suggest that you disconnect the motors and swing the detector by hand, you can then check that the voltages change as they should through the circuit from the detectors to the relays. The limit...
  12. duke37

    4-20mA repeater output!

    Which is the load resistor, is it the sense resistor R6? The op-amps do not have a common ground with the pic. The current loop has no defined voltage so that the inputs to the op-amps may go outside the permitted levels. If the loop is floating, you could tie it down with a high value...
  13. duke37

    Making a Transformer

    I think you are trying to punch above your weight. The voltage from the mains will not be affected to any significant degree by your transformer. For a simple assessment, the voltage out vs. the voltage in is due to the turns ratio. If you wish to go complicated, you could spend a lifetime on...
  14. duke37

    analog method to blink led when infrared beam is broken

    Draw your circuit, scan or photo it and post it here. Almost certainly this can be done with a transistor and a couple of resistors.
  15. duke37

    Is there something to use to flash 2 led lights quickly?

    You will need to provide a low voltage power supply and could build an oscillator from two transistors (multivibrator) as Dave says or use a 555 integrated circuit as an oscillator. The 555 could drive the led directly with a suitable series resistance. How much do you know and what are you...
  16. duke37

    higher output MOSFET

    The IRF530 can switch 14A at 100V, that is over a kilowatt. You need suitable drive and power supply.
  17. duke37

    Making a Transformer

    If the power comes from the mains at 230V AC then the volts on the primary will be 230V AC. You can call this emf if you like.
  18. duke37

    Making a Transformer

    VoltsSecondary/VoltsPrimary=NturnsSecondary/NturnsPrimary The emf at the primary comes from the power supply. The emf in the secondary is induced from the magnetic coupling. The output impedance will have a component due to the secondary resistance and another due to the primary...
  19. duke37

    LED driver transistor kind of noisy

    U3B appears to have a 100k resistor from p7 to p4, this, with the 100k input resistor gives an amp with a gain of -1 and a virtual earth (AC) at p4. In fact looking at it again, perhaps U3B is just a comparator with no feedback to give the square wave output. The two output labels seem to come...
  20. duke37

    LED driver transistor kind of noisy

    I don't understand what is going on. In particular,the SQRLFO output comes from a virtual earth so should not have any signal on it. I don't see any pulse output. You say that there are clicks on the audio signal but the circuit for this is not included. There is some crosstalk between the...
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