Introduction: OMPBB - One More Project Breadboard
It became frustrating to find and connect electronics components to my breadboard. Wires running to different power supplies, to a potentiometer connected with crocodile clips, and to an LCD readout created a huge mess and often led to wiring mistakes, accidental shorts and accidental disconnects. So decided to create a more integrated breadboard that had most of what I needed right on the breadboard. The specs are listed below:
- Integrated Power supplies
- 0-30VDC, < 300mA variable power supply
- +5V, +12V, 0V, -12V DC fixed power supplies
- 16 x 2 LCD display
- 100uA, 50-0-50uA analog panel meters
- Cat 6
- RJ11 (Phone jack)
- RCA x 4
- 2 pole 6 way switch
Have summarized the steps in a quick youtube video too.
Step 1: Figuring Out What to Include in the Breadboard and Building the Chassis
The choice of what was added to the breadboard came from what I had in my parts drawers. I have quite a few VU analog meters which I wanted to use up, so decided to include a center zero and a regular VU meter. Had an extra LCD module which would be useful to have. An old transformer based power supply from a wall wart that generated 5, 12-0-12V which would be useful to include. Plus a variable PSU based on an ebay module that would connect to another wall wart 32V supply from an HP printer scanner. And then of course potentiometers, switches and connectors which are hard to interface from a breadboard. And of course the solderless breadboard. A critical component that I had to purchase from ebay were the breakable female header sockets. These sockets would connect to the different components and allow wires to be plugged in and out.
Once I had the parts collected, I measured the dimensions of each and drew boxes to represent these parts in a graphics program and played with different layouts till I was happy with the final arrangement. The whole breadboard was designed to fit on a US letter page size (8.5 inches by 11 inches). So printed a copy of the layout and confirmed that the parts will fit.
I repurposed the top plastic sheet from a large old Summgraphics tablet as the base for the breadboard. I glued the paper template to this and cut out as many of the holes with a dremel. Then bent over the edges of the plastic sheet after warming with a hot air gun. Some more cutting of holes for the power switches and AC IEC sockets followed by inserting these into the plastic panel.
Step 2: Adding the Pots, Switch, and Connectors to the Breadboard
Now comes the labor intensive job of soldering all the parts and connectors. I glued a new paper template onto the plastic surface and then covered this with transparent film. Aligning this paper template with the predrilled holes was a headache. Would recommend that the paper be glued on first and covered and the holes drilled or cut afterwards. I inserted pieces of the female header pins into holes predrilled for the connectors then soldered solid copper wire from Cat 6 cables from the connector pins to the components. As the soldering is done at 0.1 inch pitch you have to constantly check for shorts and open connections. many instances where I had to resolder due to loose connection or a short between pins.
Step 3: Adding the LCD and Analog Meters to the Breadboard
An LCD readout is important to include in a prototyping breadboard. Had a nice little unit in my parts collection, so soldered these to the corresponding pins and then hot glued it into place. Also soldered two analog meters. After a bit of work had most of the passive components soldered to the pins. I toyed with the idea of using aluminum tire caps (to cover the tire air inlets) as knobs. the last picture shows these placed on tops of the potentiometers and switches.
Step 4: Adding Power to the Prototyping Breadboard
I soldered the AC wires - live terminal from IEC socket was connected to the power switch and the other terminal of the switch was connected to the live terminal of the accessory socket. Live and neutral wires were soldered to the AC inputs of a 5, 12, 0, -12 V supply (based on LM7805, 7812 and 7912 ICs) which came from a wall wart; and to a switch mode 32 V 330 mA supply. The 5 - 12 V supply was modified by replacing the large capacitors soldered onto the circuit board with a bank of capacitors (shown on the right) to allow the module to fit the depth of the case.
The outputs of the 5, 12, 0, -12 V supply were soldered to the female pins. The output of the 32V supply was fed to a variable power supply module bought from ebay (shown as an inset in the image). The variable preset resistors on the ebay module were desoldered and replaced with wires that led to 10K standard potentiometers. The output of this ebay module was connected to the binding posts and female connector pins. When I tested the variable power supply, the readings on the in-built LED display fluctuated. Checked for obvious shorts and mis-wiring but could not fix it. Was worried that module may not have been able to handle the 32V input though the specs indicated they could. The module had 35V capacitors so pretty close to the edge. I had an additional unused module, when I hooked this up to my bench supply, the LED digital readout did not even light up. Therefore decided to remove the display and test the module without it. It seemed to work. So placed a digital voltmeter module across the output and added a diode in series between the 32V module and the ebay variable PSU module input and connected these back into the breadboard case. Tested it and it worked. So securely taped and glued the components in.
Step 5: Completing the Breadboard ...
Taped wires to organize the birds nest. Also added a cooling fan by the power supply. Tested all connections with an ohm meter and the power supplies with the voltmeter. Screwed the bottom to the top panel. Added gray wiring nuts as knobs.
Ready to use ...!