Where it really shines is in the univibe. The 'vibe uses a dual section, reverse log taper pot that's just a bit easier to find than a dinosaur's tooth. If we notice that the pot is really wired as two variable resistors, we can use an LED/dual LDR module like the VT5C3/2, which costs about $5 from Newark and other electronics distributors. To give us good control, we use a transistor to vary the LDR current. With a single 10K pot for speed, the transistor varies the current in the LED from nearly off to a voltage set by the V+ voltage minus the LED 1 voltage and the Vbe of the transistor. You take that voltage, divide by the max current you want in your LED, and insert that resistance into Re. The 'vibe circuit has resistors to limit the min and max resistance the circuit sees. I did this in my tube univibe, and it works great. You can mess with the taper of the single speed resistor (See The Secret Life of Pots) to adjust the effective taper of the speed control pot as you like it.
Click here to download the full size of the above Circuit.
Click here to download the full size of the above Image.
Here's how to add the same thing onto a tremolo. The Trem Face is a nonstandard kind of trem, but it uses a voltage-driven version of the phase shift oscillator for an LFO. Again, cut out the dual pot, and replace it with the transistor/pot/VT5C3/2. In this design, you may want to remove LED1 to give yourself a little more voltage variation on the speed pot. Here's how to hook it into the EAN tremolo. "But wait!" I hear you saying, "The EAN tremolo doesn't use a dual pot!"
Notice that once you have this set up, the speed is voltage controlled. You can feed a voltage into the base of the transistor and the speed of the oscillator will follow it. Useful things to do this with are (1) expression pedals (2) a synchronizing signal for operating multiple pedals in synchrony (3) an envelope detector (4) a random voltage generator similar to one of the ones in the Pseudorandom LFO article here on GEO.
That's correct. The designer settled for the limited oscillation range they could get by varying only one of the two resistors available for controlling speed in the phase shift oscillator. By varying both, you get a much wider range of control from slowest to fastest.
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: