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by rfrizz
Sat Apr 27, 2019 10:05 pm
Forum: General discussion
Topic: Two Batteries, One Transistor...
Replies: 7
Views: 332

Two Batteries, One Transistor...

This is more of a general transistor question, but... I am making a stroboscope* so I will use a RPi pin 18 to control a flashlight via a transistor. The flashlight is nothing more than three LEDs in series with a resister and a 9V battery. SimpleTransistorFlashlightSwitch.jpeg What I don't understa...
by rfrizz
Sun Mar 24, 2019 3:35 am
Forum: General discussion
Topic: Stroboscope Guitar Tuner With RPi-Controlled LEDs
Replies: 7
Views: 541

Re: Stroboscope Guitar Tuner With RPi-Controlled LEDs

I hadn't known about this sort of tuner prior to your posting and now you've got me motivated to try to build up one of these. I've just placed an order for 1 Watt LEDs and have sketched out some drive circuit ideas to try out. When (if?) I get around to building something I'll post an update. I'll...
by rfrizz
Thu Mar 14, 2019 1:40 am
Forum: General discussion
Topic: Stroboscope Guitar Tuner With RPi-Controlled LEDs
Replies: 7
Views: 541

Re: Stroboscope Guitar Tuner With RPi-Controlled LEDs

Generating this signal is pretty trivial with the pigpio library using the hardware PWM. Frequency accuracy would be equivalent to the processor crystal (something like 50 parts per million) plus the discrete tune frequency step error which is also small at these frequencies. As an example in Pytho...
by rfrizz
Sun Mar 10, 2019 7:26 pm
Forum: General discussion
Topic: Stroboscope Guitar Tuner With RPi-Controlled LEDs
Replies: 7
Views: 541

Stroboscope Guitar Tuner With RPi-Controlled LEDs

I have spent a while with goog searching for answers, but I can't quite find the answers. I have seen an Arduino project for this, but I do not know how good it is, and I want to do it with a Raspberry Pi. For anyone not familiar with tuning a stringed instrument with a stroboscope, I have a short e...
by rfrizz
Sun Mar 10, 2019 4:54 pm
Forum: General discussion
Topic: STICKY: Introduce yourself!
Replies: 3497
Views: 82135

Re: STICKY: Introduce yourself!

I am not new to the forums here, but the last time I was here was around 2013. The system nuked my account, but says my old email address is still in use. D'whut? I got my first RPi at the end of 2012, and quickly became interested in electronics in general. Within two months, I designed built my fi...

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