This is the 6A schematic that was in the bottom of the unit. It is incorrect. These units have been banging around for over 40 years. Many bottoms have been switched around, due to battery corrosion in the lower case. My Geiger Counter is a 6B, and the schematic on the bottom is a 6A. When I was tracing the circuit, this drove me nuts, until I fig
Click here to download the full size of the above Circuit.
ured out what had happened. The annoying schematics do not give the Model #. This is a horrendous oversight in the documentation world. But then, the manufacturer never figured that the bottoms from 4 other types of radiation detectors would be switched around like crazy, over a 45 year period. The unit was DOA. Step 1 was to pull the PC board, and start checking things. Rather than take the time to make a tedious drawing, I simply took a photo, so it is easy to re-solder the wires back afterwards. I spent 10 years as an electronics technician, and 20 more as a semiconductor engineer. Many problems can be found simply by visual inspection, if you know what to look for, and this case was no exception. I measured the two diode junctions of the 2 transistors in the unit, and they looked fine. But close inspection revealed that the leads of the transistors were NOT SOLDERABLE when the unit was made. Four of the 6 transistor leads were tarnished beyond belief, WHEN INSTALLED, 44 years ago. The result was that over time, the lousy solder joints ceased being electrically connected. Not only can the tarnished leads be seen by inspection, but the solder did not form a proper fillet. The solder did not "wick-up" the leads, resulting in an extremely poor solder joint. Historically (1960`s), some transistor leads were NEVER properly plated with an easily solderable alloy, and many were plated with nickel, which hates to be soldered....
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: