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Tips and Tricks for Electronics Projects

Time to take a break from the PIC series for a while. Sticking with the electronics theme though I thought I'd share some tips and techniques I use in my own projects.

Making Breadboard Connectors

Many external components you use (motors, battery packs, etc) will come with connection leads that are multi-core wires tinned on the end. These work in a breadboard the first few times but quite rapidly become frayed. If you want to reuse these more than a few times it is well worth adding breadboard friendly connectors to them. This also works well for components that are do not have 'breadboard friendly' soldering connections (like switches or power sockets).

The technique I use is to take some veroboard (aka stripboard) and cut off a four hole section (see the image to the left) and use this in combination with snap off header pins to create a more resilient connector.

You simply snap off the number of tracks you need (use a pair of pliers) from the veroboard strip then snap off the number of header pins you need and then solder them to one end solder the leads to the other end. I find it is much easier to solder the header pins first as once the cables are attached it becomes more difficult to orient the board into the position you need to easily solder (remember that you are dealing with a very small board now).

You can also solder the pins in the same orientation as the board giving you a vertical insertable jumper. To do this simply add some solder 'blobs' to the veroboard tracks at the edge then hold the jumpers in place with a pair of pliers and reheat the solder blobs. A pair of helping hands is useful for this (and steady hands of your own). I tend to prefer the 'standard' attachment as it's a lot easier to solder. It just means arranging your circuit so any external connectors are placed at the edge of the breadboard and don't restrict access.

When it comes time to make your design more permanent you can still use the attached jumpers - simply include sockets in the place you would like the connection. I haven't been able to find snap off sockets (you can get snap off 'pin sockets' but they are not really suitable for this task - they are designed to accept IC's and tend to be too small to accept the header pins). I use a small saw (or a cutting disc on a Dremel type tool) to cut longer socket strips down to size.

Use a USB Charger as a 5V Supply

USB Pinout

If you need a nice steady power supply you can use a USB charger and a modified USB cable to avoid the hassle of using a wall wart and a regulator circuit. A USB charger should give you a nice steady 5V supply at around 500mA which is more than enough for most circuits. A good quality charger will simply cut out when the current drain exceeds it's capability which helps protect against short circuits.

USB Power

The easiest way to do this is to take a USB A to USB B cable, chop off the B end and solder a breadboard connector (as described above) to the two power pins. Power on a USB A connector is provided by the outer two pins (usually the red and black wires inside the main cable) - use a multimeter or continuity tester to make sure you have the right ones prior to soldering though.

I don't recommend using anything but a USB charger for this purpose (so don't plug it into the USB port on your computer for example).

Quickly Move from Breadboard to PCB

So you've prototyped up your circuit on a breadboard and now you want to make it more permanent - you can make up a PCB layout but that's a lot of time and energy especially if you only want a few (or one). It would be a lot easier if the PCB had the same track layout as your breadboard - making your circuit more permanent is a simple one to one transfer to the PCB.

A cheap and simple way to achieve this is to take plain veroboard and cut the tracks so it mimics the layout of your breadboard. Preparing the veroboards can be done while watching TV or doing any other activity that leaves your hands free (although using a track cutting tool is highly recommended). It's also worth using a continuity tester to make sure the tracks are completely severed.

You can also get PCB's that are pre-etched in the standard breadboard layout, Adafruit provide both mini and full size versions of what they call 'Perma-Proto' boards. These are a bit more expensive that standard veroboard but require significantly less effort. The image on the right is not one of these boards but a similar one I found (made by Datak, model number 21-113 - these are available on eBay at reasonable prices occasionaly).

Make Modules for Common Circuits

As you do more and more projects you'll find that you reuse circuit modules over and over - it makes sense to pre-make many of these modules and plug them in as you need them. These can be made on 'Perma-Proto' boards (as described above) using headers and jumpers to connect them to your breadboard.

Good examples of these type of circuit modules include voltage supply (put the input plug, switch and regulator on a single board), RS232 level conversion and common discrete components around standard IC's (a PIC module could include the external oscillator and an ICSP interface).

If you keep the original schematics for these modules saved away you can copy and paste them into your final circuit when it comes time to build a PCB.

Summary

These techniques have made things a lot easier for me so I hope they work for you as well. If you have your own tips please post them in the comments.