Search results

  1. Y

    Variable capacitor

    I feel your pain. I have a few. If you lived closer I'd trade for different parts you might have. People have called me a hoarder ( and even worse) but after45+ years of collecting junk electronics, I have a pretty good size junk box of materials. Difficult to find, but...
  2. Y

    Filter Choke for power supply

    I'm Bad: (or is it "My Bad"). I started talking about a 600VDc supply . Now I've shifted to 180VDC. Originally, and still do, wish to know how to calculated the needed values. I made up the scenario ,of a 600VDC transmitter. Realizing now you need more parameters I...
  3. Y

    Filter Choke for power supply

    A particular power supply I've been thinking of building is : 180 VDC for my LM-13 Freq. meter/ signal source. It needs 180 VDC at 6ma. I have a 150 VAC transformer which gives me around 200 VDC at the output of my bridge. I was thinking of a pie filter: C1 =47...
  4. Y

    Filter Choke for power supply

    Thanks guys, GPG, give me a few day s to absorb the material. Yes, Hop, I built the same transmitter in the early 60"s. I don't remember where I got the schematic. I do remember scrounging parts, and as Colin suggested, I think I just used what ever I could find. I...
  5. Y

    Filter Choke for power supply

    I remember the days when one would use a type 80 rectifier, feeding a pie, low pass filter (an 8ufd capacitor,10 Hy choke, and another 8 ufd capacitor. Sometimes the field winding of an electromagnetic speaker served as the choke. I was wondering how these values were...
  6. Y

    Filter Choke for power supply

    How does one calculate the value of a filter choke used in a dc supply. I want to build a dc 600vdc supply , pi filter, full wave bridge rectifier, 60 Hz mains supply . I have 47Ufd 800 VDC capacitors. How do I calculate inductance for the choke.
  7. Y

    Zener Diode Design

    This is a partial circuit , the one used in my ABCE1 Battery Eliminator, (the B Supply). They rectify the 120VAC transformer secondary which gives 170 VDC across the series resistor and diodes to ground. They claim that it will provide 70mA to a load. I'm basing my...
  8. Y

    Zener Diode Design

    Thank you for the Student - Hobbyist link. So if my calculations are correct: If I use 50 mA as Iz, and 70 mA I load, Izt=120 mA, using a 287.5 ohm resistor .72 Watts will be created, well within the 5 Watt maximum. From the Data sheet: 50ma is Izt minimum and 216 mA is Izm (Max...
  9. Y

    Zener Diode Design

    The data sheet for 1N3558 shows the nominal Izt, is 50 mA, (test current). I've been confused by the formulas given in different texts for Rs (series resistor) . Why not just say " use the minimum Zener test current, maybe a little more." It makes sense as you need to...
  10. Y

    Zener Diode Design

    If I use Zero Amps: Rs= (170-135.5)/ (0+.07) = 34.5 / .07 = 493 ohms, so somewhere between 152 and 493 ? So 300 would be a little more than half way between. Would this be the rule of thumb? Why not use use the Iz( min) from the data sheet and add my load current to determine Rs...
  11. Y

    Zener Diode Design

    Using the formula: Rs = (Emin-Vz)/ (Ilmaz- Iz) I z being the maximum current allowed through the Zener 5W/ 22V, I load max being 70mA I would think one wouldn't want to use Iz at max, but maybe minimum Iz to get breakdown current started and then add the 70mA. ???????
  12. Y

    Zener Diode Design

    Not sure how to upload. I scanned a sketch but it says the file is too large to upload. I've revised the supply voltage value from my first post. This is an actual working circuit, with real measured values . Hopefully I can describe the circuit: Basically at ground I start...
  13. Y

    Zener Diode Design

    I’m trying to understand how the component values are chosen for a battery eliminator circuit by reverse engineering. Original Design: Vs supply +140 V (6) 22V 5 watt Zeners In series (5) 1N2007, (.7 X 5 +3.5V) forward biased in series (1) 300 ohm 3 watt resistor (Rs) in series A 70...
  14. Y

    Need to understand power rating.

    I would check to see if its AC or DC with your volt meter. Either AC or DC will run an incandescent light. Current may be quite limited, Like suggested earlier, see what the bulb current was on the original light, if good use an ammeter to check.
  15. Y

    Use plug / jack with K Type thermocouple?

    The maintenance mechanic only cares if there is a big difference in temperatures, as opposed to the exact temperatures the performance engineer wants. If I unplug the cold junction connection and reverse polarity the temperature only changes a few degrees., and the change...
  16. Y

    Use plug / jack with K Type thermocouple?

    Typically color coding of different material lead wires are such that the color red is always negative. (USA). the other lead is colored depending on the theromocouple type. (Yellow and Red for type K),(White and Red for type J) . Voltage produced is usually in...
  17. Y

    Use plug / jack with K Type thermocouple?

    A very crude explanation, but: Most meters (measuring devices) use ISO thrermo connectors. These connectors make sure the (two) connections are at the same temperature. It is the combination of the thermocouple tip junction and the reference (Cold junctions) your device...
  18. Y

    Motor to 3phase connection compatability

    #8 wire is good for 40A, per phase. The Breaker in your panel is supposed to be sized to protect your wire to the motor, not the motor. #6 wire should be used with a 50A breaker. The motor should be protected with a motor starter appropriately sized for the motor.
  19. Y

    CRT High Voltage Power Supplies

    So, do the deflection plates have to be referenced to the 2nd anode supply polarity? I thought they are independent . ( 0V spot center, + to right, - to left). I realize the wider the deflection angle, the higher voltage needed, but how does the 2nd Anode polarity come...
  20. Y

    CRT High Voltage Power Supplies

    Do old antique electrostatic deflection television sets all use Negative HV on their CRT Anodes?
Top