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  1. AnalogKid

    DIY car taillights into lamp

    If you are asking about some aspect of the OP's question, ask it here. If it is about your own, similar question, start your own thread with a link to this one for context. ak
  2. AnalogKid

    Mixing output from 3 op amps

    1. We're still waiting for your schematic so we can make some *informed* suggestions. 2. Search the word 'baxandall' and go to images for dozens of schematics. ak
  3. AnalogKid

    What can I use instead of a 27R resistor?

    And we know nothing about your circuit. The 22 ohm will obviously be closer to the desired value, but the lower resistance might create an overcurrent situation. It *really* depends on the rest of the circuit. Please post the schematic. ak
  4. AnalogKid

    Basic circuit, but is this possible??

    Since I can't edit my previous post, here is an updated schematic. Click on the image to enlarge. ak
  5. AnalogKid

    Basic circuit, but is this possible??

    Here is a first pass at a *concept* schematic. It uses parts already in my design libraries that are not necessarily correct for this application. R3, R4, and C3 are the timing components for a standard 555 astable circuit. When power first is applied, C2 is in parallel with timing capacitor...
  6. AnalogKid

    Basic circuit, but is this possible??

    The CR1225 battery has a max rated continuous discharge current of 1.0 mA. https://www.renata.com/en-us/downloads/?product=cr1225&fileid=8fc49d179a3ce16df4e301be63 Because the battery will be discharging for only two seconds instead of continuously, I think it is safe to increase the load...
  7. AnalogKid

    555 circuit to open/close car door window

    Logic inversion, not power inversion. The 555 Trigger input responds to a negative edge. In a 12 V circuit, when the signal driving the Trigger input transitions from a voltage greater than 4 V to less than 4 V, the output goes high for the timing period. *** When the door opens and the...
  8. AnalogKid

    555 circuit to open/close car door window

    I should have put this in #9, but now I can't. Three things. 1. Having one 555 monostable circuit make two different pulse widths is not impossible, but takes many external parts. And, you need more parts to steer the one output to two different output devices (MOSFETs, relays, motors...
  9. AnalogKid

    555 circuit to open/close car door window

    As a first-pass, here is something from about nine years ago on another forum, tweaked for your application. Click on the image for a larger image. Standby current is in the low microamp range. R1-C1 is a noise filter. R2-C2 and R3-C3 are the two output pulse timers. The component values...
  10. AnalogKid

    555 circuit to open/close car door window

    The Q1 and Q2 emitters don't go anywhere. The both should be grounded. Is the goal of the project to replace the Arduino with a circuit, but the circuit drives the same two relays? If yes, then we need part numbers / coil currents for the relays. The relays probably can be replaced with...
  11. AnalogKid

    555 circuit to open/close car door window

    Does not sound difficult. But . . . To design a drop-in replacement, it is kinda important to see what you are dropping into. Please post a schematic / sketch / cocktail napkin of your complete circuit as it is now. Power connections, transistors, switches, motors, a block for the Arduino -...
  12. AnalogKid

    Basic circuit, but is this possible??

    Without simulating or prototyping anything, yes, I *think* it can be done. But the tradeoffs of LED on-time versus brightness versus capacitor size might yield unsatisfactory results.
  13. AnalogKid

    Basic circuit, but is this possible??

    An R-C network on the CMOS 555 Reset input will cause it not to oscillate for 15 seconds. After that, a separate R-C network sets the flash rate. These low-voltage 555 output stages can sink way more current than they can source, which is unfortunate for you because the Reset state has the...
  14. AnalogKid

    Basic circuit, but is this possible??

    No trolling (or scrolling) expressed or implied. All 50 items have a minimum operating voltage of 3.0 V or less, as indicated in the Voltage-Supply search parameter and the Voltage-Supply column in the results table. We know nothing about the OP's preference for DIP or SMT parts, budget...
  15. AnalogKid

    Basic circuit, but is this possible??

    TI has variations of the 555 that are rated for operation down to 1.0 V...
  16. AnalogKid

    Basic circuit, but is this possible??

    Yes this is possible. The big unknown is the light. Assuming it is an LED, we need the part number and datasheet. Next, determine how bright you want the LED to be. This (plus the datasheet) tells us how much current it needs. Next, tell us how long you want the LED to light. With this we...
  17. AnalogKid

    Powering a 5v led strip with batteries

    The board clearly has an inductor, complete with the reference designator "L1". Thus, the board is a boost converter, possibly regulated to provide a constant current rather than a constant voltage. Either way, I vote for three AA's. ak
  18. AnalogKid

    Need help to double check in this timing diagram of a latch

    Your drawing shows B changing state in-between the S clock edges. Assuming that the flipflops are standard clocked devices, not transparent latches, this is incorrect. Actually . . . The S signal is shown going into an "en"able input, not a clock input. This implies that the devices are...
  19. AnalogKid

    DIY car taillights into lamp

    With LED lights, there must be some form of current-limiting somewhere. This can be built into the lamp assembly, or into whatever control module drives the assembly. On this or other forums, someone who knows more about modern car wiring can answer that. If it is built into the lamp...
  20. AnalogKid

    DIY car taillights into lamp

    At a minimum you will need a small power supply to convert mains voltage into whatever the lights require. Separate from that, are these the lights that come on in a 1-2-3 pattern? If you, do you want to preserve that, or just have them be on steadily? ak
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