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  1. duke37

    Calculate Op Amp Gain

    Take R1 = R2 = R3 The simple equation A = (R2+R3)/R3 with 1kΩ, get 2 Complex equation A = [1+((R1+R2/R3]*(R2+R3(R2+R3)/(R1+R2+R3) = 2 Take R1 = 0.1k , R2,R3 = 1k A= 2.1k*2k/2.1k = 4.2k/2.1k = 2 so it appears that R1 is cancelled and does not affect the answer.
  2. duke37

    Why does my Royer high voltage generator switch to far higher frequency when loaded.

    I would try a couple of 1nF caps across the feedback diodes to push the fets a bit harder. The very low diode capacitance will be more effective at high frequency.
  3. duke37

    Calculate Op Amp Gain

    Thank you Harald. With 1V in, the voltage at the junction of R2,R3 will be 1V. The output will be 2V. U1 out will be 3V wih no load.
  4. duke37

    Why does my Royer high voltage generator switch to far higher frequency when loaded.

    You say it is not a power convertor, you have proved this in practise. To get a decent amount of power out, you will need to drive the gates hard but you have no feedback capacitors, only the capacity of the diodes, What mechanism is present to turn the fets off?
  5. duke37

    Isolation Transformer Earth

    The wireing looks correct but the fuse is NOT in the earth, it is in the neutral. As Harald says, it will not protect from all shocks but will only protect if you touch one place only. Steer away from microwave innards. I think the case is earthed through the transformer core but there would...
  6. duke37

    Calculate Op Amp Gain

    No, no The feedback comes from the output so the output voltage will be controlled by R2 and R3 so long as the op-amp can drive it through R1. Perhaps someone can spice it. I cannot do it at the moment due to a computer failure.
  7. duke37

    Generator Problems and Connection

    There used to be generators called Startomatics. My uncle had one to milk his cows, many years ago. It had a slow Lister diesel engine. The TV connected to it pulsed every time the engine fired. You may get some information by looking up Startomatic. It was many years prior to microprocessors...
  8. duke37

    Calculate Op Amp Gain

    The gain is determined by the feedback which comes from the circuit output, not from the op-amp output. The calculations you have shown deals with the voltage at the op-amp output which is of no concern, it will be greater than the circuit output voltage and will depend on the load.
  9. duke37

    Transistor-triggered photogate

    The way is to charge the capacitor to the high voltage with it in series with the flash gun. The SCR triggers the primary of a pulse transformer to set off the flash. Look up 'flash gun circuit diagram'.
  10. duke37

    Why does my Royer high voltage generator switch to far higher frequency when loaded.

    Please describe the operation of a Royer oscillator. What little I looked at suggested that the transformer runs in a saturated condition. The circuit I saw had two capacitors for feedback, You do not have these, presumably oscillation is due to the capacity of the diodes. A TL494 will run at a...
  11. duke37

    Calculate Op Amp Gain

    R1 limits the output current so may be to protect the amp from a short.
  12. duke37

    Transistor-triggered photogate

    I suggest you look up schematics for flash guns. These use tubes which will withstand the high voltage and are triggered with a transformer putting out a high voltage.You could even use the circuit out of a disposable camera if they are still around. I begged a couple a few years ago and was...
  13. duke37

    Help identify parts

    The relay are to aircraft standard and the asking price is $50. I Googled rbm 22301. Sort the valves into types. Do not rub the glass to get a good reading. It is better to cool the valve in a fridge and then look at it when there is condensation. I do not think there will be much interest in...
  14. duke37

    Calculate Op Amp Gain

    I would go for A since the feedback comes from the output. R1 throttles the output of the op-amp so the amp has to work harder. The frequency response and the output swing will be restricted. An ideal op-amp has a zero output impedance.
  15. duke37

    Audio troubleshooting

    What is high end hum? If it is mains frequency hum, then the reservoir capacitors (the big ones) have probably "gone off". You can test this by putting a good capacitor in parallel with an existing capacitor, If there is an improvement, then replace the old capacitor. Can you get a schematic?
  16. duke37

    Help identify parts

    The valve could be an EF50 or EF54. Is there a number on it? It is Philco which is part of Philips. The third picture is that of a sealed four pole change over relay. Very posh! It may have its working voltage on the other side.
  17. duke37

    Alternative Transistors for LM317 High Current Voltage Regulator Circuit

    It depends on the supplied voltage, it is necesary to keep well inside the safe operating area. More pass transistors there are will increase reliabilty until there are too many. Aircraft have gone from eight engines down to two to increase reliability and cost.
  18. duke37

    24v battery charger

    What is the capacitor for? All the old 12V battery chargers I have seen do not have a capacitor. The measured volage will be less without the capacitor but the peak will be the same.
  19. duke37

    Power supply rectification

    Is this an actual part of equipment? If it is faulty, what is the fault? If you are thinking of making a 24V DC power supply, then you will need a transformer, then a rectifier, then smoothing as required by the load.
  20. duke37

    Astable / scope problem

    I do not see your circuit. Many scopes need a common earth so you cannot measure the voltage across the two resistors. You can measure the voltage relative to common. Each channel can measure the voltage at one end of the resistor and some scopes can subtract the two values to get the voltage...
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