A one stop shop with fixed 5V/12V/24V/USB metered power, adjustable power supply, voltmeter, continuity tester and basic oscilloscope.
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I have uploaded initial photos and instructions but I can enhance these more if there is interest. 3D stl files and OpenScad model is now uploaded for printing and customisation
I will probably create a separate project for the AtTiny85 continuity tests. It is a very simple project but is also a good introduction to the AtTiny85 DigiSpark (and clone) boards.
Most of the wiring connections are now shown in included images. I will also add images next for the PSU, switch, fuse and XT60 connector
To reduce the desktop footprint I have added an option for an external power brick. It is equivalent to the internal one i.e. 24V 5A so requires a mod to the rear to take a 5.5mm x 2.5mm barrel jack panel mount socket. This also avoids anyone messing with mains voltage.
I did not want this to stick straight out the rear stopping it from being pushed to the back of my desk so I have angled it so that the plug is mostly enclosed and the wire drops down from the rear. Makes it a neater job.
I have updated the OpenSCAD file to include this, added an stl file for it and added some photos to show the internal and external change.
Been busy on other projects so only posting this now. Any questions just add to the discussion
A few comments on the voltmeters and ammeters. First on the housing. These all come with shells that click into a hole quite easily. This would have made the 3D model simpler but they need more space and I wanted a nice line and symmetry below the DPS3005 so the best way was to create the mounting in the 3D model. In my case the bare voltmeter/ammeter board are a friction fit but you can use a little hot glue if they are not sitting in correctly.
Second thing is accuracy. These are cheap voltmeter/ammeters. In most cases we are just not looking for precision, just a rough value, most of these are accurate to about 0.1V and some can be tweaked with a small potentiometer on the board so look out for that if it is important. Generally it is fine and I don't have to pull out a proper multi-meter.
When connecting to the ammeter it seems strange to connect the thick red wire to the black binding post but since this is the current coming from the load and the thick black wire is connected to 0V it makes sense. Just follow connections from the load.
Uploaded pictures of the PSU back case with wiring. Using fork type crimps bent to fit the case to allow the safety cover to click in place while still sliding back into the case.
Mains live wire passes through a 3A switch before connecting to the PSU live mains terminal to allow for local isolation. The 12V line connects via an inline fuse before being soldered onto the female XT60 connector.
Added a little strain relief on the mains cable with a tie wrap to prevent the cable being pulled out. I don't intend to move this much so should not get much stress.
Note: do not work with mains electricity unless you are confident working with this. Use a 24V 5A power brick and swap to a barrel jack rated at >5A.
There are 6 dc - dc buck convertors in this project, while not as inefficient as linear regulators they can still get toasty. If the supplies are only getting light use the there is probably no need for a fan, just make sure that you have the base raised (using stick on rubber feet) as there are some holes underneath for air flow.
If you are ramping up the amps then a bit of assisted airflow is worth considering. I have included mounting holes for a 60mm x 60mm x 15mm fan on the inside of the main unit. I have a few of these on order from AliExpress to try it out but not needed it yet.
If you have the full unit with the power supply then the fan will pull air though the main unit and push it through the PSU so the one fan should do the job.
The LM2596S Dual USB Power Supply Module is fairly cheap (~$1.5) and can churn out 3A (2A + 1A). If they are being pushed above 2A adding a small heat sink would be recommended (only cost a few cents but I had a couple spare from A4988 driver boards)
Wiring diagrams are now shown in png images. This covers meters, binding posts, 12V/24V selector switch, barrel socket and DPS3005. Buck convector wiring for DSO150 has been added but best to follow the JTech instructions to build the oscilloscope.
Note, when you are building this oscilloscope it is very easy to get it wrong if you not follow the pictures on the JTech guide. Particularly soldering the encoder switch to the correct side of the additional board.
Diagram for Voltmeter and Continuity Tester Wiring has been added. Programming can be done with continuity.ino file.
The continuity tester uses an AtTiny85 Digispark board, one resistor (close to 50ohm) and one active buzzer. Also only needs one line of actual code (excluding pin settings) and is a nice starting project for using the AtTiny with total project cost about $2 (+postage).
Files are:
Added 3D stl files and OpenSCAD file for customisation. Also available on thingiverse: https://www.thingiverse.com/thing:4988627
This is an intermediate level project and assumes familiarity with buck converters and soldering. The space is tight and may require a little adjustment of wires as components are added. The PSU is an optional part of the build but is fully integrated. The PSU involves working with mains voltage so do not do this part if you are not use to working with mains voltages (because…death etc). An alternative is to get a 24V 5A brick supply and add an XT60 female connector.
Solder red/black wires to the two LM2596 converters and set the voltage to 12V and 5V (24V input)
Solder red/black wires to the MP1584 converter and set voltage to 9V (24V input) and cover with clear heat shrink
DSO150 – Build the kit and connect the MP1584 converter in place of the 9V jack
Continuity Tester – Solder the buzzer and resistor to the ATTINY85 board and program Solder together the Voltmeter, Continuity Tester and selection switch and cover the attiny with clear heat shrink
Screw in all of the binding posts (6 posts, 2 sockets as in picture) with 1 nut
Screw in the DSO150 (4 short screws for the main board, 2 long for encoder switch and 1 long for the analogue daughter board
Slot in the slide switch, voltmeter
Screw in the 5V LM2596 converter to the side panel beside the DSO150
Slide in the LM2596S Dual USB Power Supply (don’t screw in until all wiring done)
Run wire between the two LM2596S Dual USB and onto the LM2596 converter
Slot in the volt/ammeter to the centre and connect to 5V and posts as per diagram
Slot in the volt/ammeter to the side and connect to on-off-on switch and posts as per diagram
Screw in the 12V LM2596 converter to the side panel below the DPS3005
Connect the DPS3005 output to the binding posts and barrel jack socket
Solder wires to the XT60 panel mount male connector and connect to all 24V inputs as per diagram (you can solder these together or use a lever nuts)
I had planned to add a few of these things but it was getting out of hand. Had planned to incorporate a component tester but was not good fit without a custom board design and was just not worth the hassle for the time I use it. I have a pick-it-up bead vacuum tool but I am working on a smaller 12V unit but separate from this. I have a different, but very simple, reflow oven design based on rocketstream's code with an esp32 or esp8266, might publish that.
The 3D print took multiple redesigns, days and days of test prints so decided to keep it to what was sensible with reasonably priced stuff that I would use.
I may be missing the info somewhere but what is the LCD on top for? It looks like a Raspbian (with the HDMI bridge and microUSB power connectors sticking out on the side). It is related to the project or is it simply stacked on top?
@gulliverrr The main picture shows a few things on my bench, second picture homes in on the multibench. The one you are talking about is another thing I am working on. It will be a case with a capacitive touch TFT, pi4 and a cheap $8 logic analyser. Still working on this but looking to get sigrock on the pi and the logic analyser in the case. Case will be the same dimensions as the multibench so that I can stack it or put it side by side. I have stacked it because I want to use the screen with my microscope for pcb inspection and smd work. The pi also has the IoTStack on github from @Andreas Spiess so I can manage home automations stuff through this (mosquitto, NodeRed, MotionEye and maybe Home Assistant). Coming soon (along with some other stuff).
Nice work. A function generator and inexpensive LCR bridge would be nice add ons. Get's cluttered when cramming all that in. So shoehorn more stuff in and add Bluetooth audio and a light :)
Function generator would be a good idea, never used an LCR bridge, just have a couple of component testers that are only occasionally used. I had more elaborate plans but I want to finish other projects. Main deciding factor for what I could fit was the power supply dimensions and the stuff I thought I would used for PCB testing, stepper and servo powering and checking led chain current requirements.
If you do try cramming all that lot in, it becomes an unmanageable mess to use due to all the cables on the front :)
Didn't put a scope in my one (somewhat smaller and built into a console type case) as all the scopes are big standalone things (except one that's in a guitar pedal).
You probably don't need an LCR bridge unless doing a lot of work making audio crossovers. Some component testers can have a fair bash at that too.
John Gilmour
Michael Murillo
Mario Ninic
Dave's Dev Lab
zakqwy
This is awesome. I have actually been planning a project similar to this but based around a soldering station. I am still working on the layout of the individual components before I start designing the controller board.
Since a soldering station has a pretty strong PSU and a hot air station needs plenty of air, most lab devices/tools can be powered off those, bringing the costs way down. For example my current soldering station has a 800W power supply which would be plenty to run a 30v 10A power supply while the iron is off. There is no reason to have both when you can't use both at once.
So far I am planning on:
Devices
-Reflow oven
-Board heater
-Air filter
-Power supply + usb charger
-multimeter
-transistor tester /lcr meter
-temp sensor
-7" display
-light / light ring
-Parts drawer, tip cleaner, etc.
Hand Tools
-Solder iron
-Hot air
-solder sucker
-soldering tweezers
-paste dispensing
-vacuum pick/place
-digital microscope
-3rd hand
I am open to adding other things that would use the same components such as an esp32, stm32, Atmega or maybe an additional ADC or other IC as long as it is not too expensive.