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USB "Solid State Relay"
I've made a simple circuit to deal with a problem in a computer lab.
It's a simple USB switch that turns off the monitor when the computer is shut down, thus preventing the monitors to spend electricity with the standby current.
Schematic:
PCB:
You can use it as you...
Ronja is a free technology project for reliable optical data links with a current range of 1.4km and a communication speed of 10Mbps full duplex.
Ronja (Reasonable Optical Near Joint Access) is an User Controlled Technology (like Free Software) project of optical point-to-point data link. The...
If the sensor gives you a pulse, you can use the CCP module for a precise value.
Made a frequencimeter with the CCP module in this post.
Modified to give the RPM.
//Using 20MHz clock
#include <16F877.h>
#use delay(clock=20M)
boolean a;
int32 rise, rise2, value;
float freq, period, rpm...
As they said, you can use the ULN2003 or ULN2004, it's a darlington array with open collector.
Here's the datasheet:
http://www.ti.com/lit/ds/symlink/uln2003a.pdf
You could make a wireless ethernet link, like RONJA.
By using infrared led + lenses you can achieve up to 100Mbps with 3~4km range, and using lasers you can communicate over 100Km.
You could make a simple frequencimeter with the microcontroller.
Using the 16f877A as example:
//Using 20MHz clock
#include <16F877.h>
#use delay(clock=20M)
boolean a;
int32 rise, rise2, value;
float freq, period;
#int_ccp1
void isr2()
{
rise=CCP_1;
}
#int_ccp2
void isr()
{
rise2 =...
I think it'll be easy to make the program work like this:
Start -> Do operation -> Sleep -> Watchdog wakeup -> Repeat.
You can use a lower clock if your procedure doesn't need much processing power (like cryptography).
If you could post the schematic we could do a efficiency check on the power...
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