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  1. duke37

    1979 sanyo receiver blowing fuses

    Put a light bulb in series with the mains input, then you will not blow a 4A fuse.. Measure the voltages at the output of the bridge and further down the line. If there is a dead short you will get no voltage but if there is a partial short you should find if it is the + or - supply which is...
  2. duke37

    Fuse confusion?

    The important fuse rating is the current (4A) but the rate of blowing should also be specified. (slow blow or fast blow) Fuses do not fail for the fun of it so you will need to find the fault. Do you have many power surges in your area?
  3. duke37

    Dumb question re. simple inverter

    So what frequency do you estimate you will get?
  4. duke37

    Dumb question re. simple inverter

    The 390R with 0.01μF will give 58kHz - far too high for a laminated transformer to handle . Posh valve audio amplifiers have trouble going to 10kHz. 1kHz would be nice. If you are going to rectify the output then the frequency is not critical and I would not include an adjuster.
  5. duke37

    Dumb question re. simple inverter

    Thanks for the welcome. I have been locked up, mending my broken spine. I managed to walk (or stumble) without a stick yesterday. My electronic hobby has been put on hold but I am off the pain killers and some parts of my brain are working again.
  6. duke37

    Dumb question re. simple inverter

    The frequency is 1/(4.4*R*C) so 390k and 0.01μF is 58Hz and 390k with 0.47μF is 1.2Hz which is far too low. Is the resistor actually 390k?
  7. duke37

    Dumb question re. simple inverter

    The frequency is 1/(4.4*R*C) someone has borrowed my slip stick so you will need to work out the frequencies yourself. 390k C= 1E-8 390k C= 0.47E-8 The frequency must be within the capability of the transformer. You can make a transformer from a TV line output transformer core with 1...
  8. duke37

    Transformer Output Current

    I do not see why a torroidal transformer should heat less. They are lighter but the winding is more difficult and it is unlikely to find a high voltage one. The core is laminated but with only one lamination, wound from a long strip of grain orientated silicon iron (how many grooves on a...
  9. duke37

    Transformer Output Current

    A transformer has a long thermal time constant so can be overloaded for a short time if left to cool between bursts. The current limit will be determined by the heating in the wires, not only the secondaries but also the primary. The magnetic field will change little with current, that will be...
  10. duke37

    Generator AVR

    A Variac would do if the generator is AC and has a similar voltage output to the Variac. The energising voltage is possibly low voltage DC. You could try using a Variac to drive a 12V battery charger to provide variable excitation and measure the resulting output voltage. Divide and rule.
  11. duke37

    Generator AVR

    You will need to find out the broad principles of the generator and regulator to determine what to test. What are the symptoms? To much or too little output. I would separate the generator from the regulator and put a variable supply into the regulator and observe the output. Let us have...
  12. duke37

    Coil position on ferrite rod?

    The coil position will affect the inductance which will be maximum with the coil in the centre. Most radios adjust the coil at the low frequency end of the band for maximum sensitivity. The capacitor is adjusted at the high frequency end of the band.
  13. duke37

    1n400X complete datasheet

    Temperature will affect forward voltage and if this voltage is held constant, then the current will vary greatly. This effect is used to stabilise current in amplifiers.
  14. duke37

    please help with my crossroad traffic light project...

    The output p3 is connected to p7 discharge. I think the powerfull output circuit will win the contest. I think that leaving p6 and p7 open and connecting the timing resistor between output and trigger, p2 will do the job, making a similar circuit to my 4093 circuit. I don't think you need C2 in...
  15. duke37

    please help with my crossroad traffic light project...

    I think I have found the circuit. It used one gate of a 4093 - simpler than a 555 - for the timing.
  16. duke37

    please help with my crossroad traffic light project...

    I made a traffic light sequencer using a4017. This was to drive full sized lights so used mosfets on the output. I must have the circuit somewhere, it will be on the forum two or three years back. Your circuit is over complicated. Just feed the 4017 output through a diode to a resistor and base...
  17. duke37

    i am designing radio transmitter and reciever

    How are you going to get a 21MHz signal from a 23MHz crystal? 21MHz is at the edge of the 15 meter amateur radio band. You should keep away from the edge in case you fall over ! To be licenced for the amateur band you will need to pass an examination and you will need to comply with the rules...
  18. duke37

    Dual inductor/single core question

    Could the tick be an arc over?
  19. duke37

    Battery charger gismo

    Thanks Kris, I don't know how you do it all. I have found on cpc.co.uk Bourns multifuse radial MF-R600-0-99 6A 30V Stock FF01367 Holding 6A Tripping 12A They have one in stock and I can buy one. I also want some other bits from them so will get an order off today. Never met one of these...
  20. duke37

    Battery charger gismo

    Looks just like the digikey picture. I would not describe it as a fuse since it takes considerable time but perhaps this is how they work. I do not know what parameters to look for, perhaps 6A 20V.
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