PIC16F84 | Electronic Project Circuits

Posts Tagged ‘PIC16F84’

Alarm Phone Dialer with MT8880 and PIC 16F84A

Just hook this Alarm Phone Dialer up to something you would like to monitor, for example, a high water alarm, low temperature alarm, back window, garage door, etc. When the system is activated it will call a number of programmed numbers to let you know the alarm has been activated. This would be great to get alerts of alarm conditions from your home when you are at work. The microcontroller code is provided on the site.

Phone Line Controller by PIC16F84

It might be “yet another” Â«deviceÂ» controller that operates over phone-line, but this one works for sure The task was to build a device that connects to the phone line and has a relay as an output switch. It should also sense if the connected Â«consumerÂ» is turned-on or off and report to the administrator at the other end of the phone line. The administrator would then call-in the device, log in with the password, and check the state of Â«consumerÂ», turn it on or off, change password or some other settings. Current version has only one relay.

Fast NiMH – NiCd Battery charger by PIC16F84A

This battery charger charges a NIMH 5-pack battery used in the BiPed robot in less than 1 hour, and charges the 10-pack NiCd used in the Snuf robot in about 30 minutes. To prevent overheating of the battery, the charging current is turned off when the slope of the battery-voltage turns from positive into negative. A second termination-criterion of the charging process is provided for safety: the charge time is limited to about 1 hour.
In the figure 2 below you find the schematics of the Delta-U battery charger. The program for the utilized PIC 16F84A is given in this file nicd.asm *). The transistor Q3 serves as a current switch, and should be able to handle the charging current. The charge current is limited by R5. This resistor should be able to dissipate the energy supplied to it. The LM311 comparator, together with the PIC serves as a simple (non-linear) ADC. The absolute ADC-output value is not important, since only the change in battery voltage is considered. The charging current is switched off when the battery voltage is sampled (each second). The resistor pair R6/R8 should be configured such that the maximum battery voltage is measured in the range 0xE0 .. 0xE8 by the ADC. Then, since the ADC is non-linear, the ADC is sensitive enough to detect a negative slope in time. Since I had a surplus on LCD’s I used one to indicate the actual status of the charger. One or two LEDs could do about the same of course.

Read More Source:http://home.planet.nl/~j_havinga/BattCharger/BattCharger.htm
Thank you.