Hand and body motions in proximity to the sensing antennas produce frequency changes in a Hartley oscillator operating at approximately 750kHz. The signal from this variable oscillator is mixed with a constant reference frequency in a ring modulator and the result passed through a single pole of low pass filter to leave only the difference between the variable and reference oscillator frequencies. The sensing circuitry is duplicated for Pitch and Volume sensor antennas. The output of the ring modulators is boosted in level by discrete transistor amps which also provide a second pole of low pass filtering because of the the feedback capacitors from collector to base. The sine wave output of the pitch sensing circuitry is routed to the VCA () for volume processing.
Click here to download the full size of the above Circuit.
The fully filtered signal is converted to a square wave by a Schmitt trigger, then differentiated to produce narrow pulses which are integrated to produce control voltages. The Volume Control Voltage is used as the control signal for the internal VCA. The front panel "Timbre" control allows a blend of sine and/or square wave to serve as the input to the VCA which consists of discrete transistors and a single stage opamp. VCA gain structures are arranged so the stage will distort when Volume is set to max. The Volume Control Voltage is differentiated to produce a Velocity Control Voltage. Velocity CV is also routed to the diff. amp input of the VCA to produce asymmetrical distortions in response to rapid volume changes. (see Panel Controls). The Velocity CV is thresholded by a Schmitt trigger to produce a gate and S-trigger outputs.
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: