AC power is supplied via AC Fuse F1 and Power On/Off switch S1 to 6. 3V filament transformer T1. Fuse F2 is provided as an additional safety feature, since a short to the filament transformer may not be enough to blow the main power fuse. Hum balance pot R1 is provided for good measure, though it`s unlikely to have much of an effect given the overa
Click here to download the full size of the above Circuit.
ll design of the amplifier. This supplies filament power to most of the tubes in the unit, as well as the #47 pilot light I1. Note that T1 does not provide filament power for tubes V1, V3, V4 and V18. V4 is a gas regulator tube, and obviously doesn`t need filament voltage. V1 and V3 are in the high-voltage regulator circuitry, and require isolated filament supplies because their cathodes are sitting at high voltage above ground; these will be covered in the HT section. V18, the first gain-stage input pentode, is treated specially to a DC supply (covered in the below) to reduce the possibility of filament-induced hum. D1 and R2 provide rectification and current limiting for metering the supply voltage. Note that in all schematics, "MP" represents a metering point; the metering circuit is further detailed in next section. Switched AC voltage is also applied to a timer relay RLY1. I used a commercial timer block for a standard octal relay, by Releco; this is rather pricey, however, and DIY timer circuits are readily available if you search the web. This timer delays for a variable time (on the order of 20 seconds) to allow all the important filaments to reach full temperature before energizing the main HT supply. The input to the timer relay is also routed through the "safety link" incorporated in gas regulator V4 (pins 3 and 7), preventing energizing of the HT supply (and very probable damage) if the unit is powered up with...
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: