Search results

Search Forums New Posts
  1. AnalogKid

    Question about op amp dual supply circuit...

    Is the Radio Frequency book available as a PDF? Thanks. ak
  2. AnalogKid

    Current Flow

    Put another way, the LED *requires* a forward voltage across it of greater than 1.5 v to 3.8 V before it will emit light. The forward voltage of the transistor's base-emitter junction clamps the voltage across the LED to only 0.5 V to 0.8 V for a typical small-signal transistor. Thus, the...
  3. AnalogKid

    Oscilloscope always showing Sine Wave

    If the sine wave always is the same frequency, like 50 or 60 Hz, check the ground clip on the probe. If the ground is floating, the scope will pick up ambient power line energy like a radio. Scope trace photo - ??? ak
  4. AnalogKid

    Resetting Latching Relay with Momentary Button

    What post #15 shows is that the controlling circuit (the relay and switches) and the load that is being controlled (shown as an LED) both run on the same power source. If you had told us this in post #1, this thread would have been finished in post #2. Shawn19 is running a similar thread at...
  5. AnalogKid

    Resetting Latching Relay with Momentary Button

    Depends on the relay. Part number / coil voltage / coil current / coil power - anything - ? Also, what contact arrangement do you need for whatever is being controlled? The basic idea is that the relay needs an extra set of contacts beyond what is needed for the task. For example, if you...
  6. AnalogKid

    Problems with my school project Automatic ON OFF lamp using LDR and MOSFET

    I don't see a resistor in series with the load. Reference designator - ? Unless you mean R15 or R16. Increasing these would make the problem worse. Other than the FET, the most significant impedance in series with the load is C9. Also, a 1N4749 is a 24 V zener. Most power MOSFETs have a...
  7. AnalogKid

    555 monostable on power delay

    You already have identified the C, and the R is the pot. This is a double-sided board. There might be connecting traces on the op side of the board beneath the IC. ak
  8. AnalogKid

    555 monostable on power delay

    What is this board? What is its function? Link to its product page? ak
  9. AnalogKid

    555 monostable on power delay

    Now that C4 is in place, I think C1 can be reduced 10x. The discharge problem is that when the switch (SWx?) is opened, there is not a good low impedance path from the Vcc net to GND. A solution is to add another 10K resistor to the circuit, from pin 8 to pin 1 (Vcc to GND). Now C1 will...
  10. AnalogKid

    555 monostable on power delay

    Add a small signal diode (1N914, 1N4148) across R1 (your schematic), anode to Vcc. This will create a discharge path around the 10K resistor. ak
  11. AnalogKid

    555 monostable on power delay

    There is no filter capacitor in your description of the offline power supply. Without one, the circuit is powered by rectified AC swinging constantly between GND and 12 V. That can't be good for circuit operation. If you do in fact have a filter capacitor, then your post is an excellent...
  12. AnalogKid

    small transmitters

    You also need a receiver, plus a huge amount of computing power, plus a SIM card reader or equivalent storage of user account information. I think the physical size of the transmitter portion of a cell phone is a relatively small problem to solve. The world is awash in billions of dead cell...
  13. AnalogKid

    Simple, or so I thought. Creating circuit to transform 24vac control to 12vdc.

    The TS was last here over two years ago. Better to start your own thread, and reference this one with a link. ak
  14. AnalogKid

    JFET "Amplifier". How Would This Work?

    Please post a link to the source of that circuit. ak
  15. AnalogKid

    OpAmp demystification

    For multi-pole active filters, the corner frequency of each pole usually is different. You can see that in your component values. The circuit in #2 and your circuit are different. Your circuit is a true three-pole filter, not a two-pole filter with an extra R-C tacked onto the front. Side...
  16. AnalogKid

    Need help about switch power supply circuit

    Your location tells us about the power distribution in your area, things such as average voltage, the typical voltage range, power quality and stability, etc. It also can tell us something about the electronic components andmaterials you have access to. ak
  17. AnalogKid

    Need help about switch power supply circuit

    Not in the hand-drawn schematic. ak
  18. AnalogKid

    Need help about switch power supply circuit

    Please post a link to the source of the circuit. The transistor symbol has no indication of its polarity - NPN or PNP. Also, which side of the schematic is the input, and which is the output? ak
  19. AnalogKid

    Problem in charging 450v 680uf capacitors at the same time

    Please post a schematic of your circuit. Note that if you are drawing 5 A from a 16 V battery, that is only 80 W. After the inefficiencies of the inverter, that leaves around 50-60 W at the inverter output, only about 1/4 A at 220 V. A bank of discharged capacitors will draw way more than...
  20. AnalogKid

    Want to copy ultrasound tooth regeneration device.

    Since others are jumping on a 5 year old thread, so will I. That is conspiracy thinking. If this worked, it would completely take over the market. Nothing is more guarantee-profitable than obsoleting needed standard equipment with new equipment. ak
Top