Apply power to the frequency counter and set the coarse (top pot) and fine (bottom pot) adjustments to show zero frequency on the display. Turn the pots counter-clockwise to set to zero. Sometimes the counter will show all squares and no digits. Disconnect and re-apply power and the digits should show. Also, turn the viewing angle of the display
Click here to download the full size of the above Circuit.
to make sure they are visible. _Install a 74HC4046 in the middle socket. This will allow VFO energy to reach the counter. (Or remove the short on the VFO cable, leave the HFO cable shorted. ) Be very careful of reverse polarity connections. A reverse polarity connection to the frequency counter will blow the voltage regulator (78LO5). Use a diode at the B+ input to the Frequency Counter if you think you might make a mistake. Band side of the diode goes to the outside where you will be attaching power. _Set the 2/8 ceramic trim pot (labeled 14. 068) to its middle position. Line up the slot in the adjustment screw with the capacitor pins, with the rotor plate on the end with the arrow. The rotor plate is the part of the top with the metallic color. If the frequency is too high, add a turn to the toroid. (This may require rewinding the toroid for a clean appearance, but having the frequency read too high, >15MHz, is unlikely. ) _Secure the VFO toroid by whatever means you have decided. Some options are a small plastic wrap, a 4-40 screw/nut and 3/16" rubber grommet (cut to fit into the center of the toroid), or pour wax from a candle (let wax cool before proceeding). Picture _Set the receiver to 40 Meters. Bandpass switch to the 40/30 side and the Crystal Filter switch to the 40/20 side. One LED should be on next to the 10. 545 relay. The offsets and the adding/subtracting are done at Pins 12 and 13 of the PIC16C71. Pins 12...
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: