Transmission line transformers, using the principle that any two wires more or less travelling in parallel make a transmission line, of impedance determined by the geometry and that impedance being suited to the circuit (not necessarily matched, as the case may be). The low frequency consequence is minimal Cp and LL for a given design.
Tim
Monitored mouse traps:
It's ugly in the sense that it looks like some kind of torture device, but it's really just a dry contact which uses foil strips with magnets to hold in place. When mouse trap trips it dislodges or breaks the strip which breaks the circuit which triggers an alarm condition. There's 3 alarm points, the 2 traps in a single alarm point are in series.
The old version used the actual trap for the conductor but it proved to be flawed as it corroded over time and I'd start to get false positives as resistance was very high.
Which reminds me, I should go up in the attic and reset the two that are tripped (been like a year lol) and also add fresh peanut butter. I really need to figure out how they're getting in in first place though, but it's hard to figure out when I only get like 1-2 per year.
my tube amplifier
with international parts , including CCCP, USA, China and germany
Pah, mine's uglier though!
...and at one point it was uglier still (with Darwin award possibilities)!
P.S. Your's is quite a work of art - I like the ground bus. Care to compare top views?
This is an RF level detector which requires only one hand to operate and is intended for locating hidden transmitters at close range; close range includes "which leaf or rock is the transmitting antenna". With a short loaded 1/4 wave antenna attached, it can located transmitters between less than 1 milliwatt and more than 10s of watts. Feedback is via an audio tone which doubles in frequency for every 6dB increase in signal strength so when the tone doubles, half the distance to the transmitter has been covered. (1) Operating frequency range is HF to beyond UHF.
An automatic gain control circuit limits the peak audio tone to about 1kHz and remembers that gain so the only control is the pushbutton switch shown which "resets" the gain. This simplified interface allow one handed operation by hearing which frees the eyes to visually search and the other hand to hold a flashlight. The automatic gain control uses a 2N7000 as a variable resistor with trimmable drain to source feedback to control the octave/dB transfer function. The 0.1uF film capacitor shown remembers the peak gain control setting.
An LT1007 provides almost all of the gain after detection. An earlier design I did based on the
one published by K0OV used a chopper stabilized amplifier for greater gain and less drift but this created problems due to slow overload recovery.
The RF detector was originally a pair of matched 1N4148s in a biased square law detector bridge but later I changed it to a simpler full wave rectifier using 1N270s which worked just as well if not better. If I did it again, I would revisit the temperature compensated square law detector bridge and maybe use chopping and transistor base-emitter junctions instead of diodes. (2) The ultimate sensitivity is better than -60dBm which is much more than can be used in the field without a narrow RF preselector.
(1) An earlier implementation produced an audio tone like a Geiger counter. This was not only more difficult to use but was found to alarm the general public resulting in law enforcement being summoned.
(2) Schottky detector diodes would be the obvious choice however they are easily damaged with overload and the sensitivity is already much better than needed.
Ohhh why didn't this forum, subject topic and cheap digital camera's exist 20 years ago. I would have supplied my home made works of art... 200 watt stereo amp in a box, 50 watt amp on a plank of wood, 3d glasses, power supplies, 3d glasses, stationary bike generator, and the list goes on. But, one photo I've kept, only around a few years old, is a natural gas hot water tank, where the natural gas was disconnected, so, I used a 120v plug in fan heater feeding the base to make hot water and it worked for a year straight making enough hot water for showers and doing dishes for 2 people during the summer, 1 or 2 people being conservative in the winter, take a look: (The heater was running 24/7 on it's low/half power mode) And yes, I'm crazy! (There was NO natural gas service to the house!, nothing in the pipes, I'm not that dumb...) Yes, that tinfoil is multiple layers thick to the point that you might be able to call it duct grade & after 1.5year of use, once dismantling, there was a brown darkened spot on the lower right of the heater's heating element.
Through those 2 previous winters, I saved around 800$ total since natural gas here in Quebec now costs twice as much as heating with just normal baseboard heaters, not to mention if you have a heat-pump for the rest of the house...
My shot at a soft starter and power saver for a 3-phase induction motor, early 1988. Instead of measuring motor load by power factor, it measured load by actual motor rpm with a Hall effect sensor and a single magnet glued to one of the fan blades. In this particular example the full load rpm of the motor was 1440 and no load 1500. The board phase controlled 3 anti-parallel SCRs and if the motor was running faster than full load speed it would back off the voltage till it got back down to that speed. Applied voltage was proportional to load. At no load it reduced the power drain to 1/6th, and rather less as the load increased. DIP switches at the end of the board set the motor full load rpm. 102 CMOS ICs and my first time laying out a board with more than 1 or 2 ICs, first time using Protel 3.08 and first time actually using a PC.(XT) Entire circuit drawn on a huge piece of paper and traced out onto the screen, pad to pad. No schematic on the screen, no netlist showing the connections, no internet to ask questions. Took 2 weeks and it worked! Only 1 or 2 minor board routing mistakes. Made 1 unit and demo'd it to the boss and then the company ran out of money and closed up. Ahhh.... to be 30 yo again and know what I know now.
Wow!, and this coming from a guy who has seen a 68040 accelerator for the Amiga 2000 with 32mb of ram done as a wire-wrapped functioning prototype and I personally designed and made a true 24bit RGB video card for the Amiga on a breadboard with ram ICs piggybacked on top of each other...
Looks just like any of the industrial logic boards I've seen over the years.
Tim
my tube amplifier
with international parts , including CCCP, USA, China and germany
How dare you, that is pretty!
Remove the terminal strips to reach ugly status.
I should go up in the attic and reset the two that are tripped (been like a year lol)
EEEEEEEEWWW!
(must have stinked up the place)
My shot at a soft starter and power saver for a 3-phase induction motor, early 1988.
I design soft starters for a living.
So, um..
Hmm.
I thoroughly commend the results of the work you've done!
Wow!, and this coming from a guy who has seen a 68040 accelerator for the Amiga 2000 with 32mb of ram done as a wire-wrapped functioning prototype and I personally designed and made a true 24bit RGB video card for the Amiga on a breadboard with ram ICs piggybacked on top of each other...
That's also impressive work. The extent of my 68040 experience is taking a 25mhz mc68rc040 and putting it in the place of a 25mhz 68LC040. Then overclocking it to 40mhz by moving some smts around and putting a heatsink on top. Nothing like designing a video card! I humbly bow to you too.
I need to get a camera working
Ugly is the new beautiful.
Not my own, but a Bob Pease design:
