The small 8-pin PIC12C508 is pre-programmed to generate our 38KHz carrier frequency by simply pulsing I/O-pin GP1 (shown above). The PIC will generate either 38KHz or 40KHz, depending on the state of GP3 when power is first applied. If you connect GP3 to ground, then apply power to the circuit, the frequency will be 40KHz. This was implemented for people using the older 40KHz style infrared detector modules. The default is 38KHz with pin #4 (GP3) left floating or (not connected to anything), Pin #7 (GP0) is to inhibit (stop) the carrier output. When GP0 is connected to ground, the PIC will halt generation of the carrier frequency.
Click here to download the full size of the above Circuit.
This is an optional control feature for power saving, and in most cases, un-necessary, but it's there if you need to use it. Ground pin #7 to inhibit the carrier frequency. Release this pin from ground to start the carrier frequency again. Connect GP1 (pin #6) of the PIC12C508 to pin #1 of the two-input NAND schmitt trigger as shown in figure 2. The data signal pin can be any I/O-pin from the BASIC Stamp or other microcontroller. By referring to the NAND truth table below, and the schematic above, you can see how the PNP transistor is held OFF by the logic "1" output of the NAND on pin #3 until both inputs #1 & #2 are logic "1". The 38KHz carrier generated by the tiny 8-pin PIC pulses from logic "1" to logic "0" at a rate of approximately 38,000 cycles per second, hence 38KHz. The serial data signal is 1200 or 2400 bps (bits per second), and considerably slower than the 38KHz carrier frequency (as shown below). You'll need a power supply that can deliver 5-volts @500mA for the circuit configuration shown in Figure 2. The Lumex OED-EL-8L, High-Power 180mW, 940nm Infrared LEDs will drop approximately 1.6V each. To figure total (peak pulsed current): 5V - ( 1.6V + 1.6V ) / 5.1-ohms = 352mA peak pulsed current.
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: