I used the original board layout shown in the magazine article as well as the original driver transistors. However, due to the unavailability of the original power transistors, I opted for a more robust output stage using Toshiba 2SA1943 and 2SC5200 complimentary transistor pairs. This transistor change also allowed me to increase the rail voltage which allows the amplifier to deliver more power. The schematic for my version of the Jean Hiraga's Super Class-A 30W Amplifier is shown..
Click here to download the full size of the above Circuit.
Click here to download the full size of the above Image.
Click here to download the full size of the above Image.
Click here to download the full size of the above Image.
Above you can see the PCB with all components, note the bias resistors which are 1W carbon types I found they had better thermal stability in this application. The heat marks at the end of the legs of the resistors next to the Sprague Orange drop capacitor are from 0.6W metal film resistors which were operating at their thermal limit and were subsequently replaced with 2W metal film types. My version of the Jean Hiraga Super Class-A Amplifier is running at a bias of about 1.65A @ 35V resulting in about 58W of continuous dissipation per transistor in the output stage (just over 1/3 their rating of 150W). As you can imagine, the heat sink runs quite hot, approximately 40 Celsius (100F) above room temperature. The enclosure work is all done by hand using aluminum. Channel sides, 3 mm top plate, 3 mm base plate. The heat sink is comprised of two pieces cut to size and is approx 420 x 180 x 35 mm. The fasteners are mainly countersunk stainless M5 or M3 stainless. Heat sinking was increased. The capacitor bank was also increased to six 220000 uF capacitors (yes that is 1.2 Farads). A 500VA potted toroid transformer was used for the supply. I have added a small toroid for a regulated supply running the DC protection circuit which I added. There is also a RF filter in the supply line. I am very happy with the sonic results of this amplifier. Jean Hiraga's deceptively simple and pure circuit topology once again shines through. The...
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: