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  1. AnalogKid

    LED strobe with fading effect possible with a NE555 ?

    BTW, here is a link to the original page for this circuit. http://www.cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html ak
  2. AnalogKid

    LED strobe with fading effect possible with a NE555 ?

    I like this circuit because it gets double-duty out of the timing current; storing it up in the timing capacitor for the delay, and then dumping it through the LED. A standard 555 circuit wastes its timing current. There is a way around that, but the flash profile will not have the same look...
  3. AnalogKid

    CD4017B has the jitters

    That looks like it has the driver transistor and transient protection built-in. You might be able to eliminate R2 and T1 in your post #1 drawing. Link to vendor page? ak
  4. AnalogKid

    CD4017B has the jitters

    The output of a TV remote is *not* a simple on/off LED. It is a series of short bursts of a (approx.) 38 kHz square wave. The bursts vary depending on which button is pressed. Your circuit probably is responding to the bursts, which explains the chattering. However, your circuit does not...
  5. AnalogKid

    Not working 12v dc to 220v Ac

    The only thing limiting the current through the FETs is the impedance of the transformer. A 5 A rating does not mean that the current through the winding is limited to 5 A. You do not say how hot the FETs are getting. Can you post a scope shot of a FET drain voltage? ak
  6. AnalogKid

    Wien bridge oscillator help...

    For my library collection. I've seen many calculator sites come and go, so I like to have two or three links for each type. ak
  7. AnalogKid

    Wien bridge oscillator help...

    Link to slew rate calculator? ak
  8. AnalogKid

    Fire alarm using a PTC as a sensor.

    There is no common ground. The input circuit, comparator, and output circuit all must be referenced in some way to the same DC potential. They do not necessarily have to be hard wired together - there are some instances where you might want a DC offset between the input and output. But in...
  9. AnalogKid

    Minimum Voltage For Capacitors

    The problem is not with the voltage across the capacitor. The problem is the voltage across the transistor. This circuit is well known. Its operation is very dependent on the transistor's reverse-breakdown rating. With most small signal transistors, it will oscillate reliably with a 12 V...
  10. AnalogKid

    Working on a 3-voice 40106 oscillator. Need help...

    Serious packaging skills. WOW. ak
  11. AnalogKid

    Never seen this

    DIP switch = 1976 or later. When the Arduino was released, DIP switch circuits had been around for 27 years. https://en.wikipedia.org/wiki/DIP_switch#History ak
  12. AnalogKid

    12vDC Two Trigger Relay

    The relay is switching the load, and the diodes are steering only the relay coil current. A low cost 1 A rectifier such as a 1N4004 should be fine. ak
  13. AnalogKid

    12vDC Two Trigger Relay

    First, consider replacing "trigger" with "control signal". "Trigger" has specific meanings in electronics, and I don't think they apply here. If I'm reading your post correctly, you need only one relay. The two control signals are: 1. +12 V from the dome light circuit. and 2. +12 V from...
  14. AnalogKid

    police lights with 555 timer

    AND, that is an excellent example of why consistent use of connection dots is *critical* in a schematic. ak
  15. AnalogKid

    police lights with 555 timer

    There are no connection dots, so those might be drafting errors. You probably can drag the vertical segments one grid square to the right to see that Q1 and Q3 are not connected to anything. ak
  16. AnalogKid

    police lights with 555 timer

    Without getting into the sim software, the schematic needs work. You need to add six small signal diodes (1N914, 1N4148, etc.) between the 4017 outputs and R3 and R5, one for each output. As you have it, High and low outputs are connected together, and the poor little 4017 is trying to short...
  17. AnalogKid

    a transistor is a variable resistor

    I understand what you are trying to say, but the way you are saying it is incorrect. In DC and AC circuits, "cancelling out" something is a specific action, and that action is not what you are describing. A power supply does not cancel anything. However, adjusting the output voltage of a...
  18. AnalogKid

    240VDc supply

    Without knowing the output voltage and peak load current, nothing can be calculated. Does random guessing actually help you? Any particular reason you are keeping all of the design requirements a secret? Which Specification(s) do your supplies have to meet? In the US military, the army...
  19. AnalogKid

    Short pulse output

    Correct. Post #7. A 555 is neither a true monostable (output pulse width completely independent of trigger pulse width) nor a true retriggerable monostable (output pulse period restarts if the input is triggered in the middle of an output pulse). To make a 555 a true monostable, you have to...
  20. AnalogKid

    Short pulse output

    Here is an innergoogle-grab of a classic NAND-gate monostable. A negative-going edge at the input (either a switch closure or the negative edge of an input pulse signal) causes a negative-going pulse at the output. In this circuit, the output pulse width is independent of the input signal...
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