Show the homemade equipment you are using now.

[Grandchuck]

Here is a simple but useful oscilloscope preamplifier.  It has 40 dB gain and a bandwidth near one MHz.  It needs shielding and that is my next soldering project.  I will use double sided PC board material.

Shielding worked a treat. 

[kripton2035]

of course my shorty-with-display ! details on the link in the signature... IMG_0686.jpg (1702.48 kB. 4032x3024 - viewed 319 times.)

[kripton2035]

also jay-diddy-b esr meter adapter, I made a digital one

[jord4231]

Signal tracer


Oscilloscope component tester before and after adding a volt meter

[Andrew_Debbie]

Battery powered Buck-Boost --> linear power supply  powering a  455kHz signal generator.

The signal generator is from an old magazine article. The power supply is my design. I've built two of the power supply modules.   The one in the photo is 5V  and 3.3V.   The other runs at 9V paired with a 5V linear regulator.

These 50x100mm modules mount on a 100x100mm plate.   I've got several other of these little 50x100 modules in work. 

[fourfathom]

I've got a bunch of homebrew test gear.  The photo shows a 10W RF attenuator, a resistive 4-way splitter, and a Time Interval Counter (TIC) of my own design and build.  The TIC has this inside:

• A 100MHz internal clock (a PLL inside a gate-array), which can be locked to either an internal 10MHz TCXO, or an external reference (such as the Bodnar GPSDO I usually use).
• Four inputs, AC or DC coupled, 50 Ohm or 10 Meg termination, >100 MHz input response.  Any of the four inputs can be used as the external reference clock
• Selectable divide-by-ten prescaler, settable 32-bit divider for each of the four measurement channels,  Rising/falling edge selection
• Timestamp capture for each measurement channel, 10 ns resolution. Event / Interval / Period / Frequency calculation and reporting
• An internal NCO / mixer / filter which provides high-resolution measurements of  narrowband high-frequency inputs (example: < 10 milliHz resolution of a 10 MHz input at a 10 Hz measurement rate)
• OLED display (the photo shows the screensaver, a scrolling sinewave to reduce OLED pixel burn)
• USB "serial port" control and reporting interface to external programs.  About 50 measurements per second max reporting rate (serial port limitations)

The chart photo shows a frequency vs temperature measurement I made this morning, testing the TCXO in a ham transceiver.  The chart shows a frequency of about 100 Hz; this is actually the difference between the 25 MHz TCXO and the internal NCO.  This shows that the TCXO frequency is varying by about 3Hz.  I used a modified "Reptile Incubator" with a homebrew controller as a temperature chamber.  Notice the frequency "retrace" as the temperature cycles up and down.

I've got lots more homebrew gear, but I had these photos handy.

[paul@yahrprobert.com]

GPIB / USB adapter.

Very nice GPIB adapter.  What design is that? It looks similar to the Galvant design.

[dobsonr741]

DDS function generator based on AD9833, VCA822, TLV5618, Raspberry Pi Pico. Controllable by SCPI and a UI, has a bonus +/-3V programmable voltage source with 12 bit resolution. Attenuator down to -60dB.

[MrYakimovYA]

8 channel thermometer. DS18B20 as a sensor. Raspberry Pi Pico (clone) inside.

[MrYakimovYA]

High Resistance Standard. For calibration of a picoammeter that I'm developing. Upper red banana jack was replaced with BNC later.

[MrYakimovYA]

Test fixture (Faraday cage) for electrometry stuff. I can measure high resistance (100 Meg with HP 34401a for example, and higher), leakage current ans son on. This boix is also intended for my picoammeter.
P.S. D-Link hub is a very important for such measurements

[MrYakimovYA]

DDS function generator based on AD9833, VCA822, TLV5618, Raspberry Pi Pico. Controllable by SCPI and a UI, has a bonus +/-3V programmable voltage source with 12 bit resolution. Attenuator down to -60dB.

Nice generator! I like it!

[HarryDoPECC]

I'm entering in the "Essential to Me but Unlikely to be Useful to Anyone Else, Anywhere" category

Wang 300 Series Keyboard Tester
Before opening the logic case to chase a non-existent fault among four hundred transistors and 1k diodes, all 60 years old, it's a good idea to make sure that the ancient transistors and diodes in the keyboard and display are not the problem.


Wang 300 Series Core Select/Drive Tester
Setting up the MSO to check that the right half-selects are being activated onto the core plane is tedious and it's useful to be able to check that the decoding logic is working and that the drive currents are about right.  The half selects flash past, Lord Knows how they did this in the day with 2 channels, 1 trigger and no storage.....

[fourfathom]

the "Essential to Me but Unlikely to be Useful to Anyone Else, Anywhere" category

Yeah, I know what you mean!  It's fun though, isn't it?

[JimKnopf]

I use a selfmade resistor decade from time to time. I once bought one from a well known chinese selling platform that looked like it was from Mao era. It was too big and not accurate enough for my purposes.

I built it from 9 (later one with 10) thumb wheels. One with old-style resistors and one with SMD resistors.

I also like to use the Retro-Chip-Tester (RCT). A do-it-yourself project. You can buy the pcb at 8bit-museum.de. The other components you have to get yourself. You can eventest and burn very old chips with it.

[jonpaul]

Popular Electronics Super Audio Sweeper restoration of 1973
https://worldradiohistory.com/Archive-Poptronics/70s/1973/Poptronics-1973-10.pdf
Still working after 50 years!

Your thoughts appreciated

Jon

[alanep]

A homemade audio distortion analyser (10Hz - 100KHz). The tracking notch filter is based on the Tektronix AA5001 and everything else is my own design. I built it back in 2003 with a few subsequent updates/changes - the last was a firmware update to the controller Nov 2022.

It uses average detection, RMS calibrated so it hasn't kept up with the latest standards. It has a residual of about 0.0014% with a 0.5V RMS 1KHz test signal from a clone of the Tektronix SG505.

It uses NE5534 opamps in the main signal path and the tracking notch filter. The tracking notch filter is a very special design by Bruce Hofer who went on to form Audio Precision (with other ex Tektronix employees). It uses Vactrols (VTL5C4) for the notch filter frequency control with very low distortion. VTL5C4s are still available but for the last 30 years, they've been made to a different cadmium sulfide chemistry and have much higher distortion. So, this unit can't easily be replicated i.e. the VTL5C4 you buy now won't be suitable (I bought mine back in 1990s). This might have been one of the reasons Bruce Hofer went to a state variable filter with "MDAC"s (major frequency control) and FET for fine frequency control in the Audio Precision equipment.

When I was designing this unit, I've found that the rotary mechanical switches' non-linear contact resistance can introduce measurable distortion when passing the signal. So I used a Motorola MC68705P3S single chip microprocessor to scan the selection switches (with DC/pullup resistors) & then to control the various relays that actually pass the signals. These relays have high quality contacts which are far better than the readily available rotary switches.

Being a "one" off, the unit was built using veroboard. With careful layout & using ground protection tracks/planes, it achieved a noise floor of -114dBm (shorted input and with 80KHz B/W filter). Please note, this unit's input is unbalanced and thermal noise is lower compared to an electronically balanced input stage (with similar devices/topology). I should explain that whilst a balanced input will have better common mode rejection (for hum/noise), it does have one downside i.e. the thermal noise contribution of the two inputs.  A designer has to work much harder for lower thermal noise in a balanced input topology...

It also includes a monitor speaker for identifying obvious problems but for better understanding of the type of distortion, you can't beat looking at the function O/P on an oscilloscope.

Anyhow, here are the pictures:

[fourfathom]

A homemade audio distortion analyser (10Hz - 100KHz).

I am very impressed.  Nice retro-looking meter, too!

[T3sl4co1l]

To varying degrees of "using now":
Bench supply (linear, +/-20V 10A or so)
GPIB-serial adapter - https://www.eevblog.com/forum/testgear/tds460-hardcopy/msg2950524/#msg2950524
High current supply/load (switching)
Lead acid battery charger, 24V 5A - https://www.seventransistorlabs.com/Images/100WPowerSupply24V.jpg
Load dump, 24V - https://www.eevblog.com/forum/projects/24v-load-ballast/msg4002922/#msg4002922
Electronic load, 500V 4A - https://www.seventransistorlabs.com/Images/ActiveLoad2.jpg
Isolation transformer (240V 15A)
Desktop and bar style LED lights (50-100W) - https://www.seventransistorlabs.com/Images/LED_Light.png https://www.seventransistorlabs.com/Images/LED_Light2.png
Digitally controlled 4 channel LED supply - https://www.seventransistorlabs.com/Images/QuadController2.jpg
EMI testing networks:
- FCC Part 15 style, 2 and 3 channel - https://www.seventransistorlabs.com/Images/LISN1.jpg https://www.eevblog.com/forum/projects/another-lisn/msg3905765/#msg3905765
- custom 20MHz+ LISN, 6 channel - https://www.seventransistorlabs.com/Images/LISN_Built.jpg
- automotive style 2 channel - https://www.eevblog.com/forum/projects/high-current-lisn/msg4576645/#msg4576645
- Ethernet 2-pair CDN - https://seventransistorlabs.com/Precompliance/Images/EthernetBreakout2.jpg
Current limiting electronic fuses (10A linear, 20A bidirectional switchmode) - https://www.seventransistorlabs.com/Images/Fuse2.jpg https://www.seventransistorlabs.com/Images/SwitchingCurrentLimitUnits.jpg
20m shortwave receiver - https://www.seventransistorlabs.com/Radio_20m/index.html

Enjoy

Tim

[ElectricPower]

Her is my little mancave:

[fourfathom]

Her is my little mancave:

OK, that's just scary.  How can any workbench be *that* neat???

But I do like the instrument "bookcase".  I definitely have to make something like that.

[ElectricPower]

Her is my little mancave:

OK, that's just scary.  How can any workbench be *that* neat???

But I do like the instrument "bookcase".  I definitely have to make something like that.

Because I cleaned properly before I took the picture

It's just a shep bookcase from an sheap Norwegian store. I think i gave around 10 USD for it

[Calambres]

OK, I'll bite 

The electronic part of my man cave:



Detailed view of my homemade equipment, all of them used quite often:



Description:

 1 - The ever ubiquitous Dim Bulb Tester
 2 - Resistor decade box
 3 - 30V max / 200mA to 10A / 60W DC load
 4 - Differential Circuit breaker (GFCI) tester
 5 - Square and sinewave analog signal generator (http://pisotones.com/GF/GF.htm)
 6 - Pi RF attenuator and dummy antena
 7 - RF amplifier
 8 - 8A - 8V to 22V DC short protected and current adjustable power supply
 9 - (under the fan) Capacitor Leakage Tester (http://pisotones.com/CLT-R/CLT.htm)
10 - 230V-230V 100W Isolation transformer
11 - Capacitor outer foil detector (http://pisotones.com/Articulos/DirCaps/DirCaps.htm)
12 - 200V - 100W - 0A to 1.5A DC load (http://pisotones.com/CF-DC/CF-DC.htm)
13 - Mr. Carlson's low voltage capacitor leakage tester
14 - +/- 0V to 32V - 1A symmetrical power supply

...and out of sight, a transistor curve tracer:



There are some other minor projects here and there... I've been making DIY electronics for decades now!

[Gyro]

Her is my little mancave:

Just a note that we have a long 'show your workbench / mancave' thread for where the general work area outweighs the home-made equipment...

https://www.eevblog.com/forum/chat/whats-your-work-benchlab-look-like-post-some-pictures-of-your-lab/

[BillyO]

I built this up a couple of months ago.  Just a cheap DC-load module in a nice case with an isolated linear power supply and set up for switchable 2-wire/4-wire mode.

I use it quite a bit for testing rechargeable batteries and other things.  It's a lot easier to use than my Siglent load, so it gets all the small, simple work.  Quite surprised how much use I'm getting out of it actually.