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[on:]

Hi,
  This is my first time using an ATtiny84 and I just wanted to verify two things.
First in the attached picture is this the correct setup for the reset pin with a pushbutton? The resistor value is 10K Ohm
Secondly does anyone have a suggestion for a resistor value between on the pins and a PNP 2N3906 transistor?
Thanks in advance for your help.

[Reply #1 on:]

(A) Yes, and
(2) I'd use 1000Ω, but it's probably not terribly critical.

 

[Reply #2 on:]

Thanks.
For the resistor is there an equation that you are supposed to use or is it just a rough value works?

[Reply #3 on:]

Thanks.
For the resistor is there an equation that you are supposed to use or is it just a rough value works?

I just go with the latter.  Don't want to load the µC pin too much, but still want to drive the transistor to saturation. I'm sure an afternoon could be spent calculating the exact proper value, but 1K has worked well enough for me.

But just to be a little more thorough, what kind of transistor, and what will it be driving?

[Reply #4 on:]

A PNP 2N3906 https://www.sparkfun.com/products/522 . It will be connected to a bunch of LEDs to turn them on and off.

[Reply #5 on:]

That's probably a 100mA load, give or take. I'd try the 1K with one LED, measure the collector voltage, add a couple LEDs at a time. If the collector voltage doesn't get low enough to drive the LEDs bright enough, try one of those 330Ω guys on the transistor base instead. If that still doesn't achieve the desired results, then a different transistor might be in order.

[Reply #6 on:]

The leds should not draw more than 160ma (8*20ma) so hopefully it will work. The description said up to 200ma. Do you think that there might be a problem, though?

[Reply #7 on:]

Nah, go for it!

[Reply #8 on:]

Thanks for your help!!

[Reply #9 on:]

Thanks for your help!!

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