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| Schwinn 3 mode Bicycle Safety Light question |
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| sambonator:
So in my pursuit to learn more about analog circuits, I tore down my Schwinn bike safety light. It has 1 button that toggles the LED's between on, flashing, and off. I've identified a 22Ω resistor, 0.95µF capacitor (by measurement), and what looks like a transistor... can anyone tell what that is? How does that allow me 3 modes of operation with a pushbutton? Attached at the pictures of the unit. Thank you! |
| Zero999:
The capacitor has 105 written next to it, which means 10 00000pF or 1µF. It's probably for supply decoupling, but there's a possibility it's for timing. The resistor no doubt limits the current through the LED. The transistor lookalike device is an integrated circuit but without the part number your guess is as good as anyone's. |
| sambonator:
--- Quote from: Zero999 on March 14, 2019, 09:01:57 am ---The capacitor has 105 written next to it, which means 10 00000pF or 1µF. It's probably for supply decoupling, but there's a possibility it's for timing. The resistor no doubt limits the current through the LED. The transistor lookalike device is an integrated circuit but without the part number your guess is as good as anyone's. --- End quote --- Thank you Zero999. Didn't realize 105 was referring to the capacitor value. Another step forward in reading printed circuit boards! ;D I'll dig around a bit to see if I can find info on this IC and post if I find it. Thank you for your analysis! |
| Kasper:
I am betting the IC is a micro controller (MCU). |
| AndyC_772:
You might struggle to find exactly what it is. Packages this small don't have room on them to write the full part number, so manufacturers use a cryptic few characters instead. Add to that the fact that it's quite likely to be an Asian market device that isn't sold in western markets, and may not have a data sheet in English. Chances are it's something like this, though: http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-8127-AVR-8-bit-Microcontroller-ATtiny4-ATtiny5-ATtiny9-ATtiny10_Datasheet-Summary.pdf |
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