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  1. duke37

    Circuit design help

    Tellus what you want the oscillation for, what frequency an voltage. The circuit you show will give an output pulse when the switch is turned on, then the mains fuse will blow or the house will burn down. Do not play with microwave transformers since they produce very high voltages and...
  2. duke37

    about diodes

    If you are using these diodes in a 555 circuit, then almost anything will do since the 555 is not that fast. stadard diodes 1000ns fast diodes 150 to 200ns ultrafast 25 to 75ns schottky <10ns The current in a 555 circuit wll be low so use the 1N4148. Any long delay for the circuit to...
  3. duke37

    relay

    The link indicates that there is some problem with suficient output from the PIR. I have not looked up the details of the IRF510 but I think it is a standard power fet. These need about 10V to turn them on fully. You will need a fet with a low threshold voltage (logic level) but these may not...
  4. duke37

    3.3v psu

    Why not use an LM317T? This will give a more consistent output and has a current limit.
  5. duke37

    Car Water Temperature Sensor

    My friend has a 1957 Hillman Minx car which has a water temperature sensor which is a little out of calibration. TT/1200 by Smiths Industries The supply is 12V which then goes through a thermal meter, (shows maximum at zero current), then to the sensor which is screwed into the engine with...
  6. duke37

    Easy Way to Extract Hydrogen Gas From Hydrogen Peroxide?

    My ancient chemistry tells me that hydrogen peroxide is wter with an exess of oxygen (H2O2) so you are not likely to get hydrogen out of it untill it is converted to water (H2O).
  7. duke37

    Brewery Circuit

    I gathered that you were not in the UK from the mains voltage. Damn George III. The power supply will cotain a transformer, rectifier and capacitor and perhaps a regulator. You can get the old style, heavy supply or the newer, light switch mode supply, perhaps in a 'wall wart'. You will need...
  8. duke37

    Simple way to salvage a car charger?

    Most car alternators are set for 13.8 to 14.4V. The battery should be fully charged at 14.4V.
  9. duke37

    Brewery Circuit

    I am only 4 miles from Swanwick, I will have to check that things are working right. :) The relay(heater) is the SSR. The relay(pump) could be a SSR.
  10. duke37

    15VAC Dual adjustable regulated PSU 5V-25VDC

    To get more output you will need more input. The input will need to be at least 2V above the output. C2 and C6 put input ripple to the regulator reference. This will negate the purpose of the regulator.
  11. duke37

    Power amplifier

    You cannot transform a low power signal to a high power. Do you mean that you wish to control a high power supply to give an output of up to 12v at up to 15A/ What will be your supply?
  12. duke37

    For designing 50v,100v,150v dc power supply.

    If you do not need accuracy of the voltage, you can get away without stabilising the output. Here is a circuit using a 36V-0-36V transformer which I think may work. You may get to within 10%. Capacitors could be 10uF, 100V Diodes could be 1N4007 I think the current drain is negligible...
  13. duke37

    For designing 50v,100v,150v dc power supply.

    I have found a simple circuit using the 555 chip. It is from dos4ever.com. It does not seem to have very good output voltage control. You may be better to get a built one.
  14. duke37

    Help wanted with a counter.

    There are several ways to detect the movement of an object. 1. A light source (led) with a light detector. It depends on the design of what you have but you can get mouldings with both devices in, separated by a slot. Devices are also available which work on reflection. 2. A swinging...
  15. duke37

    For designing 50v,100v,150v dc power supply.

    As I understand it, the actuator is a 0.6uF capacitor without a DC load. It depends on how quickly you need to change the voltage. You could make a 200V power supply and feed the actuator through a resistor which is shunted to ground with a transitor to give the voltage required. An...
  16. duke37

    For designing 50v,100v,150v dc power supply.

    What is a Piezo stack actuator? Please give details of the supply required. Is this DC or AC and if AC, what frequency? What power/current is required?
  17. duke37

    LED arrays

    You do not need a calculator if you can do division. Have you got a slide rule? What leds are you using? To get a string of 4 leds to run on 6V, then each led must run at 6/4V = 1.5V (hard maths). I do not know such leds. The total current will be the current/string times the number of...
  18. duke37

    Help: Motor Question

    Epoxy glue will stick to most things (but not grease). I have used wooden pulleys on motors (several watts) and all I did was to make the pulley hole a little small so that it was an interference fit.
  19. duke37

    Newbie Needs Help With Transistors

    Crackling can be caused by faulty elctrolytic capacitors sparking over internally. If you can drop the power supply voltage and the crackling goes, then this is the likely cause. Otherwise check the power supply capacitors for leakage and distortion.
  20. duke37

    Looking for oscillator and frequency divider schematics

    I first met a bistable in a Clyne organ (valves) 60 years ago. The trouble then was that two resistors were not matched. More recently the Monarch had a tendency of dividing by three, I forget what solved that. Mullard "Reference Manual of Transistor circuits" 1961 "For effective triggering...
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