HackerBoxes 0018: Circuit Circus




Circuit Circus: This month, HackerBox Hackers are working with analog electronic circuits as well as techniques for circuit test and measurement.

This Instructable contains information for working with HackerBoxes #0018. If you would like to receive a box like this right to your mailbox each month, now is the time to subscribe at HackerBoxes.com and join the revolution!

Topics and Learning Objectives for this HackerBox:

  • Build a microprocessor-based component test device
  • Hone PCB assembly and soldering skills
  • Understand the use of various electronic components in circuits
  • Review test and measurement techniques for those components
  • Complete a ten lesson Modern Electronics course
  • Complete a ten lesson Analog Electronics course
  • Explore applications and limitations of sound card oscilloscopes
  • Exercise techniques to prototype circuits on breadboard

HackerBoxes is the monthly subscription box service for DIY electronics and computer technology. We are hobbyists, makers, and experimenters. And we are the dreamers of dreams.

Step 1: HackerBoxes 0018: Box Contents

  • HackerBoxes #0018 Collectable Reference Card
  • Electronic Component Test Device (Solder Kit)
  • Modern and Analog Electronics Kit
  • 140 Piece Wire Jumper Kit
  • 830 Point Solderless Breadboard
  • 3.5mm Audio Breakout Module
  • 3.5mm Audio Patch Cable
  • Two 9V Battery Clips
  • Exclusive "Elite Technology" Iron-On Patch
  • Exclusive HackerBoxes Quad Decal

Some other things that will be helpful:

  • Soldering iron, solder, and basic soldering tools
  • Two 9V Batteries
  • Computer with Sound Card
  • (optional) USB Sound Card **
  • (optional) Digital Multimeter

Most importantly, you will need a sense of adventure, DIY spirit, and hacker curiosity. Hardcore DIY electronics is not the easiest hobby, but when you persist and enjoy the adventure, a great deal of satisfaction may be derived from persevering and getting your projects working. Just take each step slowly, mind the details, and don't hesitate to ask for help.

** Sound Card Note: Step 11 discusses optionally using a USB Sound Card.There happened to be a number of these on hand as surplus at HackerBoxes HQ. We threw them in FOR FREE as a bonus gift in a limited number of RANDOM #0018 HackerBoxes. If you did not receive one, please note again that they were randomly given out freely (without impacting the budget for the box). They are not included on the contents list above and therefore cannot be considered a "missing item". If you would really like one, they are available for purchase here. Thank you for understanding.

Step 2: Automata, Penguins, and Clowns

The Exclusive HackerBoxes Quad Decal is designed to be separated into four miniature decals each perfectly sized for project enclosures, mobile devices, laptops, or toolboxes.

The Glider Symbol is featured on one of the miniature decals. It is a pattern of five dots arranged within a grid. That specific pattern travels across the board in Conway's Game of Life (a well known cellular automaton). The glider has been proposed as an emblem to represent the hacker subculture, since the Game of Life appeals to hackers and the concept of the glider was born at almost the same time as the Internet and Unix. The Wikipedia entry explains that this emblem is in use in various places within the subculture but it is not universally liked. If you do not like it, hack it. Either way, we suggest that you get a "Conway's Game of Life" program or app and play around with it. ALife!

What's up with the clown? The clown fan art and the "Circuit Circus" theme are allusions to the iconic Circus Circus Hotel and Casino in Las Vegas. Perhaps we will see you in Las Vegas this summer for DEFCON25?

Step 3: Modern and Analog Electronics Kit

The HackerBoxes Modern and Analog Electronics Kit contains over 80 electronics components. Many of these can be useful while experimenting with the Electronic Component Test Device.

These components along with other contents of HackerBox #0018 comprise everything needed to perform all of the experiments in the Modern Electronics and Analog Electronics online courses presented later in this Instructable.

Step 4: Electronic Component Test Device - Introduction

We all know the annoying challenge to identify the exact parameters of a component in the old junk box. Conventional approaches of identification and measurement are generally difficult and time-consuming. This test device is here to save the day using a very clever microcontroller-based design. Best of all, it is supplied in kit form so you get to build it yourself!

Once completed, we will automatically detect and identify pinouts for NPN and PNP transistors, FETs, diodes, dual diodes, thyristors, and SCRs.

Resistances up to 50MΩ can be measured with a maximum resolution of 0.01Ω. Three test points allow simple testing of potentiometers.

Capacitance of 25pF-100mF can be measured with a resolution of 1pF. Equivalent series resistance (ESR) is measured for capacitors over 90nF.

Bipolar Junction Transistor measurements include the collector-emitter current amplification factor, the base - emitter threshold voltage, the collector-emitter leakage current, the base-emitter threshold voltage, and the high current gain. Darlington transistors are identified. Protection diodes for power transistors and FETs are detected.

FET parameters measurements include gate-source threshold voltage, drain-source resistance, and gate-source capacitance.

Additional features:

Frequency measurement 1Hz-1MHz

Period measurement up to 25kHz

DC voltage measurement up to 50V

Square wave frequency generator at various frequencies

10bit PWM generator (1% - 99%)

Digital Thermometer (DS1820) Reader

Temperature / Humidity (DHT11) Reader

IR Sensor Protocol Decoder (uPD6121 and TC9012)

IR Encoder


Processor: Socketed ATMEAG328P (28 pin DIP)

Color Display: TFT with 160x128 pixels and 16-bit color depth

User Input: Rotary Encoder with Pushbutton

Input Power: 6.8-12VDC at Barrel Connector OR 9V Battery

Current Consumption: Approximately 30mA

Step 5: Electronic Component Test Device - Bill of Materials

Start building the kit by unbagging the components into a small tray and carefully familiarizing yourself with each component.

There are 24 axial-lead resistors having 12 different values. They all look very similar. We suggest taking a few minutes right now to look up and carefully note their values onto the paper tape attached to the resistors. The resistors are not interchangeable. If each resistor is not placed into its proper location on the PCB, the test device will not function.

This resistor code calculator is very handy. Be sure to switch to the "5 stripe" tab. Some "process of elimination" might be necessary when two sets of color stripes look very similar.

Step 6: Electronic Component Test Device - Transient Voltage Suppression

The component tester kit includes three tiny surface mount components - an 0805-sized 100nF capacitor, an 1812-sized P6KE6V8 Diode, and a SOT23-sized SVR05-4 diode array. These are completely optional components to support Transient Voltage Suppression (TVS). The tester will work fine without them, so unless you have a microscope and SMT experience, we strongly suggest you start by throwing these components away.


The purpose of the TVS protection circuit is to improve the likelihood that the microcontroller input pins might survive discharge current when a charged capacitor is connected to the test inputs. Even with the TVS circuit installed, protection is not guaranteed. Therefore it is very important that capacitors always be discharged before measuring with the competent test device.


The three SMT components should be soldering first. The capacitor and the single diode are not polarized and may be soldered in either direction. The 6-pin diode array however has a polarity markings that should be aligned with the makings on the PCB silkscreen.

Step 7: Electronic Component Test Device - Small Components

Start by soldering in the 24 resistors. Make sure they have been correctly identified by their color bands. Be very careful to place the correct values in the correct positions on the PCB. Resistors are not polarized and may be inserted in either direction.

After a through-hole component is soldered, the lead should be carefully clipped from the rear very close to the PCB surface. Always wear safety glasses when snipping wire leads.

Next insert the 9 ceramic capacitors being sure to match the values printed on the capacitors to the PCB markings. These capacitors are not polarized and may be inserted in either direction.

The two electrolytic capacitors look like black barrels. They are the same value, but their leads are polarized. One side of the cap has white stripe. This is the negative side. The other lead is the positive side and should be aligned with the "+" marking on the PCB.

The Red LED is polarized. The longer wire lead should be inserted into the square metal pad hole.

The five TO-92 devices are semicircular in cross-section. Match the orientation of this shape up with the outline marked on the PCB. Note that there are four completely different types of devices in TO-92 packages, so be sure to match the numbers printed on the packages with the designations on the PCB.

Finally, the 8MHz Crystal is not polarized.

Step 8: Electronic Component Test Device - Larger Components

Next insert and solder the larger components. These are fairly self-explanatory, but here are some pointers:

The three blue screw terminals should each be oriented so that the side ports face the edge of the PCB for inserting leads.

The arm of the ZIF (zero insertion force) socket should be left in the UP position while soldering.

The DIP28 socket should be soldered in without the chip inserted. Align the half-circle marking on the PCB to similar shaped formed into one edge of the socket. Once the soldering cools on the socket, the chip can be inserted according to the same semi-circular pin-one marking.

The 8pin display socket gets soldered to the main PCB. The 8pin male header is soldered to the backside of the TFT display for mating with the socket.

Two brass standoffs and four bolts are used to stabilize the display module once it is inserted.

Four brass standoffs and four bolts are used to form feet on the rear of the main PCB. These feet prevent the trimmed leads of the soldered components from scratching the desktop, as they can be quite sharp.

The 9V battery clip leads are soldered into the holes labeled 9V at the left side of the PCB. The red lead goes into the "+" terminal.

Step 9: Using the Electronic Component Test Device

Once power is applied to the Component Test Device, it can be powered up by pressing the rotary encoder down (there is a push-button integrated into the encoder). There is a calibration process than can be performed by shorting the three test points together. You can optionally skip the calibration for now and jump right into trying out some components to test in the next step.

A highly detailed document entitled TransistorTester with AVR microcontroller and a little more is frequently updated and available online. This document covers the design, use, and theory of operation for the various incarnations of these instruments. Definitely check it out.

This page has a whole variety of related resources in different languages.

Step 10: Ten Lesson Online "Modern Electronics" Course

Everything you will need for the PyroElectro Modern Electronics online video course is included in the HackerBox Modern and Analog Electronics Kit.

While exploring the lessons on resistors, capacitors, inductors, diodes, and transistors, take a second to test the component under investigation using the Electronic Component Test Device.

Once you learn more about how each component functions in a circuit, you might want to go to the big document for the Electronic Component Test Device and review the theory of operation to discover how the tester is able to interrogate the device under test using a simple AVR microcontroller. Many of the techniques are very clever and demonstrate useful approaches for your future design or test work.

Lesson 9 on the 555 Timer is a great opportunity to play with the frequency measurement function of the Electronic Component Test Device.

Much respect for the work done by PyroElectro on these lessons.

Step 11: Ten Lesson Online "Analog Electronics" Course

Everything you will need for the PyroElectro Analog Electronics online video course is included in the HackerBox Modern and Analog Electronics Kit.

Note that the 3.5mm audio patch cable can be cut in half to create two sets of "probes" for use with the Sound Card Oscilloscope discussed in this course. The stripped wire leads should be tinned with solder for easy manipulation without fraying.

While the exact circuits shown in the course are presumed to be safe, it is worth noting that the sound card inputs on your computer are only designed to handle a range of around -0.8V to +0.8V. When dealing with larger voltage ranges, the signal will need to be scaled down as to not overload the sound card inputs. Here are some excellent notes from Make and also from Daqarta.

If you plan to experiment broadly with sound card oscilloscopes and want to have some extra insurance against damaging your sound card, you might want to pick up an inexpensive USB Sound Card for some added electrical isolation.

The particular oscilloscope software suggested in the course is specifically for use with Windows. For Linux, there is a similar program called xoscope. For OSX users, there are various notes online about using Audacity as a sound card oscilloscope. For those who work with MATLAB or GNU Octave, look into the audiorecorder() function!

Much respect for the work done by PyroElectro on these lessons.

Step 12: Hack the Planet

Thank you for joining our adventures into modern analog electronics test and measurement. If you have enjoyed this Instrucable and would like to have a box of electronics projects like this delivered right to your mailbox each month, please join us by SUBSCRIBING HERE.

Reach out and share your success in the comments below and/or on the HackerBoxes Facebook page. Certainly let us know if you have any questions or need some help with anything. Thank you for being part of HackerBoxes. Please keep your suggestions and feedback coming. HackerBoxes are YOUR boxes. Let's make something great!

16 People Made This Project!


  • Fandom Contest

    Fandom Contest
  • Sensors Contest

    Sensors Contest
  • Frozen Treats Challenge

    Frozen Treats Challenge

34 Discussions


2 years ago

Hey so i just finished mine and having some strange, probably assembly based behavior. The screen illuminates but no text appears except, *sometimes*, it begins flashing "Short probes!"... Im able to get there kind of by randomly playing with the function menu (at least, I think thats how I get there). I short them, it keeps flashing "short probes" for a while then gives me the Hi/Lo resistance, then displays C0, then shuts off.

Any advice would be helpful, even if it's just "you might need to start over".

7 replies

Reply 2 years ago

also it says hi and lo but Ri_Hi=~120 and Ri_Lo=~2k, so I'm not sure what it means and cant find it in the docs.

Other strange behavior: After turning on, sometimes it doesn't go to calibration. The LED turns off as well as the screen, momentarily, before the backlight comes back on.

I attached some images if that helps


Reply 1 year ago

When I assembled this kit initially, I had very similar symptoms. For me, a visual inspection revealed that one of the pins going to the IC socket was not well-soldered. Soldering it fixed everything.


Reply 1 year ago

I'll chime in here -- my first recommendation is to get a magnifying glass or jeweler's loupe and a good bright light, and examine every solder joint carefully. You're looking for solder bridges connecting thing that shouldn't be connected (these can be really tiny, sometimes), and for bad or missing solder joints. Google for images of good and bad solder joints to get an idea of what you're looking for. Basically, if the joint looks like is has a line or crack, looks like there isn't enough solder, or if it looks balled up, then reflow the solder or add a touch more.

In my personal experience putting together these sorts of kits, 80% of the time it turns out that I forgot to solder something, 19% of the time I made a bad joint/bridge somewhere, and 1% of the time it's something else.

Also, while you're at it, be sure that the polarized components are placed in the right orientation.

If a visual inspection doesn't turn anything up, then break out a continuity tester and begin making sure that there are solid connections where there should be. Follow the traces between the various parts and be sure there is actually continuity between them. Where possible, measure the continuity from the parts side of the board rather than probing the soldered connection itself (you're trying to find bad solder joints that aren't visibly apparent).


Reply 1 year ago

I should also mention the resistors -- it can be infuriatingly hard to accurately distinguish between certain stripe colors on them, so it can be easy to put the wrong values in. Double-check them. If in doubt, measure them with a multimeter (you might want to desolder one lead when you do this, to avoid measurement errors that can occur when testing values in-circuit).

This is probably not the issue you're having, but I thought I'd mention is for the sake of completeness.


Reply 2 years ago

It seems my button pressing probably wasnt doing anything. It shows me battery info if I wait long enough then switches to the short probes calibration step


Reply 1 year ago

Have you figured out the issue? mine does the samething and now it is just showing 1-3 >100nF


Reply 1 year ago

anybody wanna chime in? otherwise imma consider it and myself a failure


1 year ago

Finally got around to building the tester, way behind on my kits! Apparently I've done something wrong, checked all my connections and redid some of them but no luck. Any thought of what might be causing this?


1 year ago

Completed mine, but I think perhaps the micro may be faulty. On initial power-up it waits until I depress the encoder to start, but then never responds to a depression of the encoder. Can move through the menu after it times out after the first measurement, but cannot select any of the menu items. I do see that the encoder push button is not shorted, as the LED blanks each time the encoder is depressed. What did I screw up?


2 years ago

I have a problem with the audio cable included in the kit. The wires are so small and I am having a hard time knowing which is the insulation and which is the wire. I dont think that this wire was intended for what we are using it for and the one that is in the instruction video looks like it would be much easier to use. I would like to buy a cable already done that way i could get down to finishing the courses.

1 reply

Reply 2 years ago

Tinning the thin wire with solder can build it up so that it is easier to work with.

Note that you can also use a "3.5mm Audio Breakout Module" and an uncut 3.5mm cable to "breakout" the audio cable pins onto a solderless breadboard. It requires more parts, but it is certainly "easier".


2 years ago

I used to work on an SMT assembly line, so I figured I'd try assembling the component tester with the surface mount parts.. I soldered everything up, cleaned the board, plugged in the battery and... .nothing. Completely dead. Turns out if you put the diode network on backwards the board won't work. At all. It also turns out that it's really really hard to read the markings on that part if you get any flux on it. So... I re-cleaned the board and found my error. I had to remove one of the screw terminals so I could get to the diode network. I got it turned around and my component tester works now(!) Thanks Hacker Boxes - I've been wanting one of these for a long time.

4 replies

Reply 2 years ago

the diode network is a pain to solder but i can do it if i can figure out how it is oriented i cannot see a mark for orientation does the lettering orientat it ie. dose the "V" mark the first pin (and the dot) like most dip packages (pin 1 is lower left when reading the lettering)

that has got to be the smallest part i have ever concidered soldering i started electronics at the end of tubes and the begining of ICs


Reply 2 years ago

it's really hard to see but the pin one indicator on the diode network is the dot. It needs to point to the same pin as the dot on the pcb


Reply 2 years ago

found the dot it was where i thought it should be under the "V" in the lettering easier to solder then i thought, some paste solder and plenty of flux it's a beutiful thing


Reply 2 years ago

it was easy for me to find the marking on the chip, but not on the board.
the "1" pin had a weird symbol, but i tracked the ground path the be sure.
"1" is away from the screen if anyone still wonders...


2 years ago

Does anyone know what the pin mapping is for the TFT? I am trying to get it to work with the Arduino TFT examples. I've also tried the Adafruit ST7735 libs/examples too. Any thoughts?

1 reply

Reply 2 years ago

Hi Kevin -

This doesn't exactly answer your question, but I just got done posting a short post on how to update the MCU code on my site. Nothing fancy, just a starting point, but it works....mostly :)


You might be able to get the info you need from the C files used in the directories I mentioned in the tutorial. Hope you get it working!


2 years ago

We're looking into this for you to see if we can figure it out. Just as a random note, when a transistor is drawings too much current (overheating) it may likely be due to one of the resistors around it not being the correct value.