slow but steady progress - Tue, Aug 3, 2021
new inventory, planned kits and other projects
Another trip to BG Micro today, a few parts cabinets were retrieved with labelled and organized inventory which was previously listed for sale at BG micro.
There is an overwhelming amount of stuff I need to list, and I've recently been trying to develop an amplifier kit with the HA1388 integrated audio amplifier IC.
I have a working model of a single channel amplifier, and all the parts except dual audio-taper potentiometers
For the heatsink(s) on this unit I have some to-3 heatsinks which can be drilled to fit. The challenge is to findan enclosure that will fit two of these heatsinks, or otherwise how to fit two onto one heatsink, which would likely entail bending the leads 90 degrees
I also have some JW miller coils; 2.2 and 4.7mH, which are excellent as filters for this kind of thing. And there is no shortage of regulated power supplies for these around here either
And speaking of flters, my good friend at bunkerofdoom.com has a very impressive "Brick wall" audio filter design, for use with HAM and CB radio, with sharp cutoff at 3.5Khz which requires special and very expensive chokes (less than a quarter ohm per millihenry). I was able to find what should be satisfactory chokes, so it's just a matter of tweaking the design and the layout.
Another kit or assembly I intend to make is a relay board using hella relays, which are a high-current automotive relay. They are spst, one end of the relay has two pins tied together, but the copper content and the size of the contacts is impressive, for a relatively small relay.
I hope to make this relay kit arduino compatible, using PC123 optoisolators and the house numbered 2n4401 equivalent transistors, which is the part I have in most abundance, by far.
For the relay outputs I have the weico 5 and 6 position terminal blocks.
There are a few more projects wrth mentioning which have been lingering in my mind for quite some time.
The first PCB I ever designed was for the oscilloscope graphic artist.
It worked as well as the other versions I have seen out there on the internet. Something was wrong with the circuit as shown in the article, and I ran out of time back then to mess with it.
But now I have a quantity of TL074 operational amplifiers which would work great for this.
Along the same lines, I am quite interested in the lorenz attractor and other chaotic systems as seen on glensstuff.com
I ran across his site again the other day, and realised I had not just dreampt that stuff. It is like something out of as dream, especially the 3d projection unit and the 'analog character generator'
The last project I will mention is straight from the genius at bunkerofdoom.com
It was something he originally built in the 70s, and the original unit is likely still sitting in someone's back yard shed
I believe the intention was to make a "frequency changer" but the unit was capable of all sorts of audio effects
At it's heart are a frequency to voltage converter and a voltage to frequency converter.
The idea is to take an incoming audio signal, amplify it until it's clipping, or basically a square wave with an op-amp, then feed that into a frequency to voltage converter. The output voltage of the frequency to voltage converter is fed into a voltage to frequency converter, through a potentiometer or other mechanism that would allow the level to be offset
The output signal is from there fed into either a ring modulator or a balanced modulator, and it is modulated to the envelope of the original audio signal. Something like that.
According to him there were some crazy effects that it could generate, but F-V and V-F devices are still quite expensive and precious few of those are on hand.