It was once an experiment with the AD161-AD162 pair. I still use it almost every day. At first, I did not like the voice very much but I enjoyed it as I listened. Especially the frequency at which speech sounds are very clear and understandable.
I’ve been looking for a couple of AD161’s for a couple of years ( probably eighteen years ) in the coolant that’s been removed and a couple of AD162’s.
A friend of mine sent the AD162 out of his hand, so we went to work. Although our expectation was not very high, we were able to use both the benefits and classical amplifiers at the yine.
After quite a few searches, I started to draw on the following diagram so that I could fit the existing cooler. I had to redraw the same half of the circuit in order to make the two cooler, and I made a few changes on the schematic as well.
Firstly, the feedback did not work with the 6.8nF capacitor mentioned on the resistor, it just grizzled and stopped. I put it in the place of 470pF and it was gone, I even canceled it completely. I am trying BC327 instead of AC153 and BD140 at the same time.
Since the transistor here is getting a little hot, we thought it would be nice to put it on the surface, which would be superficially in contact with the cooler.
The circuit was configured to be completely independent from each other on a single plaque.
I fed both channels with separate feeds.
The solder face and layout of the devil were printed by serigraphy.
However, since the pattern drawn to print the settlement plan is not very clear, it has not been smooth on the press, but it is also managed by this, DIY work.
I saw a little too high, so I wiggled the wings a bit. 🙂
Due to the narrowness of the ground we put some parts on the solder side.
Meanwhile, I applied a different method to cover the copper tracks.
It was not good because it was the first time but it could be improved in the future.
We took the solder from the small box sold as sludge solder, liquid solder, paste solder and ran abundantly on the copper tracks.
I then covered it with a thin layer of aluminum.
As the gray matter melted and soldered, I pushed it all the way up to cover it all the way up, but continued to spread a lot of solder in the form of small balls (collective needle head). I started to finish it around without cleaning up more dangerous. Pcb was a bit roasted in the meantime, and some of the small letters were left in place. It may be better to try one more seafarer with a solid hot air gun.
As a result, this material called paste solder should be transferred to the heat that needs to be converted into a solder within a short time and then left to cool down in a very short time.
One of the most important considerations is the mounting of the transistors to the cooler .
All of the output transistors are on the same cooler, so all of them must be properly isolated.
We choose a suitable material as thermal insulation material or we get a thermal pad.
We put it on the cooler and we cut holes with the maket knife from the related places.
We insulate some of the screws with a suitable piece of cable or sponge so that the screws passing through the transistors do not come into contact with the cooler.