Barbouri's Electronics Projects
Restoring vintage electronics along with designing and building new circuits. One eye looking into the past, the other looking into the future.
Electronic projects that I work on in my spare time.
With eleven power supplies already, I really didn’t need another one for the bench. Especially one from the early 60’s that was rated at a maximum of 6 Volts and 500 mA of output power. But this one is a somewhat rare Power Designs Inc. model 605 precision power source.
The Victor 204R is different, but very much the same calculator as the Victor 204 Medalist originally produced by Victor Comptometer Corporation. I picked up this calculator at a better than bargain price, that was almost a giveaway.
After repairing the Nakamichi 610 FM Tuner / Preamp back in late 2023, I have been on the lookout for a FM tuner for the workshop audio system. Since I already had the Hafler DH-110 Preamplifier, I set my sights on the DH-330 FM tuner which has the same styling as the 110 preamp.
This time I am working on another radiation scaler/counter which is quite a bit different than the last one. This one is a decade newer from 1975 and was built by NMC (Nuclear Measurements Corp.). It has a built-in proportional counter, but has external inputs for Geiger-Mueller, Scintillation, and other sensors.
After installing a dual-input power transfer panel for power outages at the house, I was in need of a large battery for powering the second UPS input on the panel. The first input on the panel is for my backup generator, but I wanted some power available until the generator was able to be started and at night when power usage would be low and the generator could be shut off.
I was able to pickup a non-working Nicolet Integra 40 oscilloscope for a bargain price. It was built in 2000 and is a 4 channel differential input unit capable of 20 MS/s with 12 bit digitizers and color screen.
Once again, I was donated a pair of Infinity Infinitesimal speakers by the same generous person, who donated the “System One” rack and three Nakamichi BlackBox series units from a previous post.
After the restoration of the Nakamichi 620 amplifier last year, it had been working great for 6 plus months. Then one day I turned it on and there was no sound output. Luckily the speaker protection circuit did it’s job and no speakers were damaged. The right channel had it’s output shorted to B+ (53 volts).
I finally decide that I had pushed my luck far enough with my battery backed NVRAM in my Tektronix TDS 380 oscilloscope. The specifications for the Dallas Semiconductor DS1644-120 Timekeeping RAM state that it is good for at least 10 years at 25°C, and mine had just turned 28 years old.
I decided to take a gamble on purchasing a Power Designs Inc. TP330 triple output power supply. It was a bit rough looking with a bunch of stickers on the front panel, but no scrape marks from past sticker removal visible. The seller stated that the bottom analog meter was non-functional, but the output terminals measured voltage that changed with the voltage knob.
I was generously donated three Nakamichi BlackBox series units, by the same person who donated the “System One” rack from a previous post.
The units were in great condition, and more than likely could have been used as-is. They also surprisingly came with their original owners manuals, which usually get misplaced or lost over the years.
I did not take any pictures of the initial refurbishment of the Nakamichi 610 control preamplifier as it was mainly cleaning and capacitor replacement. But as soon as I thought the work on all the components of the System One rack had been completed, one of the dB meter lamps failed in the 610 preamp.
Included in the rack of Nakamichi “System One” equipment I recently acquired was a 600Ⅱ two head cassette console. This is the same rack that was involved in a building fire and the previously repaired Nakamichi 620 amplifier.
I was kindly donated a Nakamichi “System One” rack of audio equipment recently. Overall the equipment was in good shape, but had been in a building fire and suffered from significant smoke damage. There was not any detectable heat damage and only minor water damage.
After successfully repairing the 610 FM Tuner / Preamp I decide to tackle the model 620 audio power amplifier next.
I managed to snag a Monroe 430 calculator that was in good condition and a reasonable price. The Monroe 430 is 14 digit four-function calculator with memory, percent, and a few other extras. I have worked on a model 425 and 420 in the past so I kind of knew what I was getting into, especially the lack of documentation.
Welp, another calculator tale of woe. This time it is a Monroe 650 calculator found on eBay. The 650 is the top-end model of Monroe’s 600 series calculators. It is a 16 digit Nixie tube display calculator with addition, subtraction, multiplication, division, square root function, and two memories. It operates in fixed decimal or floating point modes, and has 5 changing indicators spaced every increment of the base-10 exponent of three from the decimal point.
The price was right and included free shipping.
