Introduction: Practical Circuit Construction With Strip Board
This Instructable documents the 'minimum' tools necessary to create reasonable quality electronic circuits and gives pragmatic construction tips finishing with a practical design exercise.
It is assumed all components are low power 3v3 - 5v and are based around 0.1" pitch devices and as such does not cover surface mount technologies.
Pictured above are typical circuits I have designed in the past using these tools and following this construction process.
This is in no way a guide to professionally produce circuit boards but is meant to help inexperienced electronics enthusiasts and makers to produce something more permanent than push fit prototyping bread boards allow and consequently is merely a collection of practical tips I have acquired over many decades of successful making.
Please note : You follow this guide at your own risk.
Step 1: Selection of Prototyping Board
There are typically two types of copper laminate prototyping board available;
Veroboard (strip board) or perf board (picture above). In both cases they usually come in the form of paper reinforced phenolic as opposed to the more professional glass reinforced epoxy (picture above).
My preference is to use Veroboard over perf board as the resultant designs require less solder and thoughtful layout creates a far better aesthetically pleasing design.
Step 2: Re-sizing the Prototype Board
Once a component layout is know the prototyping board can be cut to suit. Copper laminate is expensive stuff so use it sparingly and save any off cuts for later.
Cutting is achieved in the following way;
- Place the board on a cutting mat
- Align a metal ruler along the perforation holes where the cut is to be made
- Using a sharp knife (safely), repeatedly score the board top and bottom along the straight edge (5 or 6 times), running over the perforations.
- Once the board has been scored it can now be easily bent and snapped.
- Finish off the rough edge with a flat file or sandpaper.
For longer cuts the board can be gripped in vice to gain better purchase during the snapping step.
I have seen scissors used to cut Veroboard, but this generally makes a real mess and can shatter the board not to mention destroy the scissors.
Step 3: Forming Veroboard Link Wires
When using Verobard to create your circuit, links will become a very important part of the design.
The lead forming tool shown above along with the video detail how you can quickly, reliably and consistently create wire links for your circuit.
It can also be used for component lead forming. ie resistors.
Step 4: Soldering
There are lots of opinions surrounding how to solder. My 'two penneth' would be the following;
Choice of Soldering Iron
You could spend a lot of money here and achieve the same results. I possess three soldering irons; an ancient Weller PU-2D temperature controlled Curie point tip, a Hakko FX888D and a Weller WSM-1C. I would suggest something similar to the PU-2D. The main stipulation being it should be temperature controlled to somewhere around 250Deg C, or approx. 480Deg F. Use a canonical tip which has a slight flat edge allowing good contact with the joint and can flood in the heat fastest. If your iron doesn't come with a dock or stand, buy one.
How to Solder
I use 60/40 tin/lead rosin impregnated solder not the unleaded variant. It is by far and away the best solder to use.
I have always got the best results by following these steps;
- Always solder on a heat resistant surface unless you are happy to live with small burn marks.
- Using a wet soldering iron sponge wipe clean the iron tip once it's up to temperature.
- Let the tip temperature settle and apply a little fresh solder.
- Pre-flux the joint to be soldered. Even if you are using the rosin impregnated solder.
- Always aim to solder the joint in one take.
- Line up the board and component and lock their relative positions, I use tape or press the board flat with one finger (equally you can bend the leads out once inserted in the board, but this can give shorts on complex boards). This reduces the chance of a dry joint if movement occurs during cooling. This is also a good time to check you can get the iron into the area you want to solder.
- Apply heat to the joint with the flat of the tip (if it has one), this heats the joint up quickly.
- Apply the solder to the iron tip first as close to the copper surface as you can and let it flow into the joint as it melts.
- Leave the tip in place for about half a second and then draw it away by pulling it up the lead of the component being soldered. This generally gives a nice convex curve to the solder joint.
Once the soldering is finished cut the remaining component lead off as close as reasonably possible to the board as you can. Use flush cut snips, they tend not to leave sharp edges that would snag and cut your knuckles. Remember to grip or put a finger over the lead before you cut it to stop it from flying off. Beware they can fly with quite some speed so protect your eyes.Some hand tool manufacturers sell flush cut side cutters with a safety clip like the Xcelite 175M which are designed to stop wires from 'pinging' away. I have a pair, but to be honest they're useless and don't give a good flush cut.
Make sure you keep these offcuts as they always come in handy later.
Don't leave a switched on soldering iron unattended or you're asking for trouble.
Always be clothed when soldering, closed toed shoes, jeans and a long sleeved shirt (believe me this is good advice).
Always solder in a well ventilated area. You could use an activated charcoal filtered vacuum pump. Better still have this and a vacuumed soldering iron tip. To be honest, I've tried the many contraptions inflicted upon me over the years. I've even knocked up a few 'Heath Robinson' variants of my own, as in the pictures above. I've always found what works best for me is to slowly breath out through my mouth, directing the air flow up over my face as I solder (I can hear the H&S people shudder as I type). Truth be known I'm more concerned about the long term health affects of mercury in my amalgam fillings to worry about a little lead poisoning.
Assuming you follow my advice. Don't put the solder in your mouth and wash your hands thoroughly after use.
The trick is to handle the stuff as least as possible.
When you get a burn, and you will, if it's bad seek medical help and give up on electronics, otherwise douse liberally in cold water and remember to be more careful next time.
Oh, and once switched off, leave the iron for a while before attempting to touch the tip (at least 10 to 15 mins). They can hold their heat for some time.
Step 5: Correcting Mistakes - Desoldering
As with all things complex there is always the chance you will make a mistake during the soldering process.
Correcting a soldering error is simple to achieve and requires one of the following options;
- De-solder braid.
- - Good Points : Easy to use, just place braid over the joint and press with iron. Doesn't heat stress the solder joint so much as a solder sucker. Re-applies flux to the joint.
- - Bad Points : Is not re-usable.
- Solder sucker
- - Good Points : Draws solder away in one action. Is reusable.
- - Bad Points : Pump needs to be regularly cleaned. Pump 'Kicks' when trigger is pressed, which can displace the tip requiring joint re-heat. Hard to line up. Can suck the copper track right off the board.
Again, always aim to complete the process in one clean, swift action.
Solder braid comprises flux impregnated woven copper strands. To use, place the braid over the joint and heat with the iron. The heat of the iron will conduct through the braid and reflow the solder joint. As the solder melts the braid will 'wick' the solder away from the joint and soak into the copper weave.
The solder sucker is a resettable, one shot vacuum pump with a Teflon end. To use, place the soldering iron on the joint to reflow. Once the solder has melted, offer the tip of the pump to the joint and press the trigger button. The pump fires and sucks the solder off the joint.
It's a matter of personal preference as to which you choose. I use de-solder braid.
Step 6: Hand Tools
When fabricating Veroboard designs I have been able to get away with the following minimal set of tools;
- Good quality vice : A third hand for soldering and can be used to help break Veroboards after scoring with scalpel. Also can grip the Veroboard whilst reshaping with the round needle file.
- Flush cut snips : Used to trim off long leads, cut link wires to size etc.
- Good quality scalpel (preferably one which can take a type 21 curved blade - Swann Morton) : Used to score Veroboard prior to breaking and very accurate cutting of copper tracks.
- Small metal rule (or hard metal straight edge) : Used for measuring and a straight edge when cutting Veroboard.
- Link forming tool (homemade) : Used for what it says on the tin.
- Flat blunt or point nose pliers : Multiuse, forming link wires and component leads, holding components during soldering etc.
- Good quality solder sucker : Used during de-soldering process
- Pin vice : Used for widening holes in the Veroboard
- Round needle file : Used for shaping holds in Veroboard
Note : I am assuming unlike mine, your vision is good and doesn't require correction for these types of tasks.
Step 7: Power Supplies
Also another area which can cost you a lot of money.
I use four main PSUs;
- RIGOL DS832 : High power multi supply rail accurate for complex electronics development (expensive)
- Wier 4000 : Reasonable power single supply rail for general electronics development (costly)
- YuRobot 3v3/5v reg. : Designed specifically for push fit prototyping bread boards and dual rail is possible. (cheap)
- Home 'rolled' USB adaptor : Mainly used as a breakout board for USB (cheapest)
Items 1 and 2 are prohibitively expensive in this context.
If you are only developing low power, simple circuits on a limited budget then option 3 is your best shot and can be adapted for both breadboard prototyping and finished Veroboard design. Its use also gives some upstream protection by virtue of the fact there is a diode and load regulation in place and comes with smoothing caps. As it uses a 2.1mm jack for it's supply you can find a home for all those redundant PSUs since it will accept a wide range of voltages at its input.
As for option 4, I have seen some Instructables making use of the USB port for supplies. I really don't recommend this as you can't put in place any regulation on the 5v rail (or diode protection for that matter), it will be noisy, so no good for analogue designs and you will lose a hub at some point, worse still blow the USB port on your PC. If you really must use the raw USB 5v, stick a hub between your electronics and the PC and put an inline fuse in +ve supply rail. In the picture above you can see I have placed a solidstate fuse rated at 250mA to protect my hub. Or you could even purchase a 5v wall adaptor (picture above).
Step 8: Test Equipment
Yet again a topic which can demand bottomless pockets for minimal return.
You've only got to watch Dave Jones on the EEVBlog 'bleather away' on the topic of DMMs to know its a huge and expensive subject and apparently garners a lot of passion.
I possess a few DMMs (pictures above);
- 1 off Fluke 87 v : Very good and accurate DMM. (expensive)
- 1 off Wavetek DM78A : Great little DMM for prototyping, even has analogue range indication. Only reads Volts and Ohms (less expensive)
- 3 off Mercury MTB01 : Purchased as job lot from Ebay. Used just to give an indication of V or I. (cheapest)
I generally use the Wavetek, as its small, handy and I mainly want to check voltage and continuity. So it fits the bill well.
Quite frankly as this Instructable is pitched at the inexperienced electronics enthusiast, we can dispense with all the snobbery surrounding measurement instrumentation and take a pragmatic view.
If you are on a limited budget and just beginning to dabble with electronics you can't go wrong with option 3. Given, most of the time you will generally be checking voltage, resistance or testing for continuity.
However, some points you should note if you purhcase a cheap DMM.
- Never use it to test mains supply. They invariably lack the necessary input protection. I have seen them explode when used to check UK mains (240VRMS@13A) after having inadvertently selected the current range. Remember you only get the one pair of eyes!
- Always make sure you have the correct range selected 'BEFORE' you attach the probes.
- Don't always believe the value you read is accurate. After all it's a cheap meter.
- Get a meter with audible continuity checking. So you don't need to look at the display when checking your work.
Step 9: Design Exercise : ESP8266-01 Programmer
As I needed to make myself an ESP8266-01 programmer board for a recent home automation project, what follows is how I went about documenting, designing, prototyping, building and testing the programmer.
Always document your design (including construction notes and anything else that's relevant). It's good practice and helps when you come to test it and can be used to create a facsimile if and when required.
You don't need a fancy design package, Fritzing, though limited is free, as is the reduced functionality free version of Eagle. In this instance I opted to use pencil and paper.
When creating designs I usually aim to; create a diagrammatic layout, Veroboard layout, circuit diagram, set of data sheets, package of software, take relevant pictures and create use case details (instructions on how to use the device).
- Quick to make.
- Doesn't damage the PC when in use.
- Small in physical size.
- Reusable both at system and module level (ie. can be used to programme many ESP8266-01s and the FTDI module can be redeployed when necessary).
- Doesn't require a housing.
- Can be powered from a range of 2.1mm PSUs. ie. whatever I have hanging around at the time. Typically 6v - 12v DC.
Start with grabbing all the relevant data sheets you need and keep copies, be thorough. I scoured the internet and found wiring details on the ESP8266-01 via the www.ESP8266.com community page which was a great starting point. As I had a spare Proto-Pic www.proto-pic.co.uk FTDI adaptor which has inbuilt level shifting (3v3 <=> 5v) I decided to use this to connect to my PC. However, from the datasheet I determined it can't safely source enough current for both itself and the ESP8266-01 so I added a simple load regulated 3v3 supply in the form of an LD1117v33. I drew a little pin out diagram of the TO-220 package next to the circuit diagram to remind myself how to connect it up correctly (picture above). Why use a TO-220 package you may ask? Simple, I wasn't sure what 2.1mm power adaptors I may have at hand at any given time and wanted to size the power capability of the series shunt regulator to cope with a wide range. So needed a device that could handle the power dissipation (without attaching a heatsink) and had a lot of thermal mass (well, enough mass to cope with the current spike during the flashing of the ESP8266-01).
Finally, as a precaution I added the 1K resistors in the TX and RX lines to limit and current in case I inadvertently shorted the leads.
As this is as simple design I dispensed with component numbering. However if you have a complex design you should uniquely number each component such that they can be easily identified.
Given this is a low current and low frequency application (ie. no external processor clock XTAL to set up), I opted to use push fit bread board for prototyping (picture above). Since the ESP8266-01 has a 2x4 0.1" connector I needed to fabricate an adaptor to allow me to fix it to the bread board (construction pictures above). Ok, I could have just used 7 off 0.1" push fit f/m prototyping leads, but I really don't like using long wires where RF is concerned, also as I wanted to do some work with the Nordic NRF24L01 LNA and an adaptor like this would come in very handy, so I made two.
After wiring up the circuit I tested the prototype using a blink example and the Arduino IDE (once the environment set up to programme the ESP8266-01) and all worked fine.
My design is now complete and the components chosen.
Step 10: Gather Components and Layout Your Board
Right, so now you have a proven circuit design and have selected your components its time to transfer the design to Veroboard.
Gather the components, lay them out to get an idea how big things are and how they will fit relative to each other or you would like them to fit (you may have enclosure constraints you need to account for or mounting holes to add).
I transfer my circuit designs by viewing from the top of the Veroboard 'down through it'. What I mean by this is I visualise the Veroboard as being transparent and view the copper tracks running left to right.
Using paper, 'pencil' (so you can rub out your mistakes) and a ruler, I then draw a series of thick parallel lines running left to right on the page and draw in a set of lighter vertical parallel lines top to bottom.
The thick lines represent the copper tacks underneath and lighter lines are only there so you can visualise the perforations. You can miss off the vertical lines if you wish, but I guarantee you will end up getting things in the wrong place when you come to assemble the board, they are brilliant for helping you align your components.
You can use graph paper for this but it's not as good as described above as the vertical lines really need to be lighter otherwise it confuses the eye.
Draw in any necessary mounting holes so you can immediately note areas on your board where routing or component location is not allowed.
Lightly sketch in where you want the main components to lie, using their actual footprints. Typically this would be power sockets, IC holders, connectors etc.
Now on a node by node basis draw on vertical interconnection lines. I tend to make the link wires as I go and lay them out in their approximate relative positions as shown above.
What does node by node mean? Each point in your circuit which connects to another point is a node. I have included two pictures depicting a typical node point between the FTDI TxO and the ESP8266-01 Rx pin, for both Circuit diagram and Veroboard Layout.
For simple boards I do this sequentially by eye. For complex boards I print a copy and mark off the node points as I cover them on the Veroboard design.
I have detailed some of the shorthand I use when creating a Veroboard layout in the next section.
Finally : When you think you are done, always finish off by doing one last node by node review of your design. you never know where a mistake may have crept in or an unnecessary track break that can be removed.
Step 11: Veroboard Layout Shorthand
As I state above, over the years I have developed a kind of shorthand for my Veroboard layout diagrams. I've included a few of the more common ones I use above.
The breaks/cuts are pretty obvious as are the links. However, I have found it useful to show a link (or component for that matter) 'bent' around a cut, simply as a reminder to apply the break during assembly, since it is easy to forget to cut a track if you run a link over it.
For resistors, I standardised using MRS25 through hole variants very early on because they're not that big and can carry 0.6W. As a consequence they have a minimum horizontal bend of 0.5" as shown 'end on'. Anything less than this and you need to mount 'side on' with suitable lead bending.
I also included two diagrams showing how you can easily route signals and form crossovers without the need to physically cross over wires on the board.
One useful point to note though. Don't be quick to cut a track as it may come in handy to form a common rail. Or alternatively there may be no need to cut it. There's no point making extra work for yourself.
After a while you'll find routing becomes 'second nature' and you can spot typical patterns by the shapes of the links; In Order, Reverse Order, Crossover etc.
Step 12: Assemble the Board
Using your design from earlier the first order of duty is to fabricate the board by scoring and cutting to size.
Next drill any mounting holes and widen any holes to accommodate any none standard parts. Better to do this now than risk shattering a board after hours of careful soldering.
Now create the strip board track breaks before any soldering is attempted so the board will safely lay flat on a cutting surface. Also doing this action up front makes it a lot easier to compare with the Veroboard layout than it is once components have been added. When cutting tracks, 'mark twice cut once'. I find it best to locate an end point via its X and Y coordinates as given on the Veroboard Layout, and be consistent. Always use the same indexing method, X then Y or Y then X it doesn't really matter just keep it the same to minimise errors. Once a cut point is located I poke a piece of wire through (remember those offcuts I told you to save earlier) and invert the board. I cut the track by inserting the tip of the scalpel into the perforation and pressing gently (you don't need much force to get a clean cut). This is repeated three more times. I have included a HiRes picture of what you can achieve with a scalpel. Don't waste your time with a box cutter or one of those 'x acto' knifes.
Once this is complete the next action is to solder in the components. Here, you should always start the smallest height items first, so begin with the wire links you created and build up from there.
Insert the links then place some insulating tape over them to hold them in place. Now invert the board as shown.
Apply pressure to the board with one finger during the soldering process (picture above). This helps keep the links held in place flush with the surface of the board. Solder these in place, let it cool, then turn the board face up to inspect your work.
If you notice any 'wonky' wires/components you can re-heat and push into place. Though a word of warning. Don't do this too many times (as I've said more then once, always aim to complete the soldering in one smooth operation), Push into place with the tip of the pliers not your finger, for obvious reasons and don't push too hard before the solder has had chance to melt, or you will strip the copper from the board.
For DIL sockets solder one pin at each corner and turn over to see is the carrier is still flush with the board. If it isn't grip the board in one hand and apply your index finger to the carrier (don't touch the already soldered pins) apply the reheat process and gently push the carrier flush as the solder melts.
Now clip the excess leads off (remembering to prevent any flying pieces of wire from escaping) and start on the next biggest items.
Repeat process until all wires/components have been soldered in place.
Note : It is normal for the tape to exhibit slight melting as a result of the soldering process.
Step 13: Test the Board
Now you need to test your board BEFORE you apply any supplies.
Use your DMM in continuity checking mode and 'ring" through each node to make sure they are indeed correct and there are no dry joints. Here's where those offcuts come in handy. You can use them to wrap around your probe tips so they poke into female connectors, chip carriers etc.
Once you are happy the circuit is correct you can try a powered test.
If you have any socketed ICs or devices remove them, if feasible. Apply power and with your DMM set to volts, check those important and expected voltage levels.
If all goes well and no 'magic smoke' is released, you can try a system test with all ICs, devices plugged in.
ie put it all together.
At this point if you've been following these tips (assuming your circuit design is good) you will have a working board.
Finally, follow these system level use case steps to check the board.
ESP8266-01 Programming Instructions
- Correctly configure Tools -> Board and Tools -> Processor for this device. (See Instructable 'Setting Up the Arduino IDE to Program the ESP8266-01')
- Ensure your code compiles as expected with no errors.
- Plug in supply to programmer board
- Plug in USB connector to FTDI and PC
- Connect Arduino IDE to correct port. Tool -> Port. Check windows device manager if you can't tell.
- Press and hold 'FLSH'
- Pulse (press and release) 'RST'
- Release 'FLSH'
- Press 'Upload' button in Arduino IDE
- Wait until program uploaded. Detailed in progress window at bottom if Arduino IDE.
Step 14: The Finished Article
The finished article in actual use along with documentation.
- 1 off Veroboard strip 7cm by 3cm
- 1 off LD1117 - LDV33V 3v3 800mA Series regulator
- 1 off 0.1uF Ceramic Capacitor
- 1 off 10uF Electrolytic Capacitor
- 2.1mm Power Jack
- 2 off 10K Resistors
- 2 off 1K Resistors
- 1 off 6 pin male molex connector
- 1 off 2by4 0.1" pitch female connector
- 2 off tactile SPST push buttons
- Various 22 swg tinned copper wire