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  • waltercf commented on kumaran512's instructable Bluetooth SmartRoom5 months ago
    Bluetooth SmartRoom

    Nice project! I think there might be a mistake in Step 6's schematic, the connection from the Load should go to the N.O. (normally open) side of each relay contact instead of the N.C. (normally closed) side. Otherwise the micro will need to keep the relay energized all the time to allow the existing wall switch to control the light. You could do it the way the schematic shows, but it seems counter-intuitive; normally you'd want the relay energized to turn on power to the load.

    Nice project! A couple of comments. First, I think there might be a mistake in Step 6's schematic, the connection from the Load should go to the N.O. (normally open) side of each relay contact instead of the N.C. (normally closed) side. Otherwise the micro will need to keep the relay energized all the time to allow the existing wall switch to control the light. You could do it the way the schematic shows, but it seems counter-intuitive; normally you'd want the relay energized to turn on power to the load.Second, you shouldn't need 2W resistors for the 10K resistors connected on pins 12-15. At most there'd be 2.5 mW across them, so an 1/8W resistor is more than enough. You can use a 2W resistor, but they are more expensive than smaller ones (e.g. 1/4W or 1/8W).

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  • What Does it Take to Build a Simple Circuit?

    Good introduction to electronic components! I think there is a mistake in Step 5: Inductors, in the last paragraph. It should say "if you put two 10 micro henry inductors in series, their equivalent inductance is 20 micro henries."

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