You’ve found a cool 555 timer project online or in my book, procured all of the parts, wired them up on a breadboard, and are now ready to power up your newly made creation. Time for the moment of glory. You slide the power switch on and… nothing, it’s not working how you expected, or worst case scenario – the magic smoke escapes one of your parts.

It’s happened to the best of us and will continue to do so. These have been my four most common 555 timer circuit mistakes, and are common in most other breadboard projects.

Wiring/Placement Mistake

I would say this is the most common cause for error that I have experienced, especially with breadboard circuits. All it takes is for one wire or part to be off by one hole on the breadboard, or you have a particular component flipped around backward, and your circuit will probably be rendered inoperable.

Solution: Double, even triple-check your wiring. Ensure all chips and polarized components are placed in the correct orientation. Methodically follow the current flow of the schematic in comparison to your breadboard circuit.

Wrong Component

Almost a tie for the most common problem I’ve experienced is using the wrong component. An incorrect value of a resistor, capacitor, etc., is easy to do with small, sometimes cryptic labels on parts.

Solution: Similar to the wiring mistakes, carefully check each component label to make sure it’s the correct value.

Low Battery Voltage

Your circuit works perfectly once, but not the second time you test it, even without changing anything. The timing is off, LEDs are barely lighting, what the heck is going on? After checking many iterations of a circuit or leaving it on for a while, that 9-volt battery may only be at 7 volts, and things may start to get a bit wonky. The 555 is fairly immune to supply voltage differences. However, when a battery nears the lower end of its capacity, the increase in internal resistance of the dying battery reduces the available current to the point of rendering your circuit or device useless.

Solution: If you notice any of the issues mentioned above, fire up your trusty multimeter and make sure the battery voltage for your circuit is at an acceptable level.

Capacitor Leakage

After thoroughly troubleshooting every tip mentioned above, the timing cycle of your project “hangs.” An LED should turn on and then off in monostable mode but instead stays on, or your astable mode circuit doesn’t oscillate from one state to the next, etc.

If your circuit uses a large value timing capacitor (usually for longer timing periods), the culprit of the behavior described above could be a leaky capacitor. What is capacitor leakage? When basic electronics are taught using the water (hydraulics) analogy method, a capacitor is usually represented by a pipe with a perfectly sealed flexible rubber diaphragm in the middle that prevents water from passing through.

To use that analogy to describe capacitor leakage, the diaphragm isn’t perfectly sealed, and a small amount of water (current) does leak through. Large electrolytic capacitors are known for having a higher leakage current than most other types. This can cause issues for time-sensitive circuits.

Another way to visualize leakage current is in the diagram to the right. Imagine a resistor in parallel with the capacitor allowing a small amount of current to pass.

I have had a brand new 50-volt, 1 uF electrolytic capacitor by one manufacturer only charge up to 2 volts when 9 volts were applied due to high leakage current. All of my other caps by different manufacturers with the same ratings worked fine. It took me a while to figure out what was going on.

Solution: For more critical timing applications tantalum or Mylar and other film type caps usually work best. If you have to use electrolytic caps, at least use low tolerance, high-quality ones. You can usually find the leakage current specs on the manufacturer’s data sheet.

Wrapping Up

These are the most common errors I’ve run into while working with breadboard circuits. How about you? What have been your biggest 555 timer circuit mistakes? Give everyone a heads up of what to look out for in the comments below!

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In this video, I show what the completed projects from Chapter 7 should look like.

Errata:
Project 5 parts list – Optional caps C4 and C5 are shown in the schematic and breadboard layouts, but not listed in the parts list. Both should be .01 uF

The post My 555 Book, Chpt. 7 recap: Audible Anarchy with the Atari Punk Console appeared first on Bent-Tronics.

In this video, I explain the basics of breadboards, and how to transfer a simple schematic to a working circuit on a breadboard.

Buy the book here.
Buy the complete parts kit here.

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Things have been a little quiet on the blog, but behind the scenes, I’ve been a writing/editing/formatting/coding/building/designing/marketing/coffee-drinking machine! Two years ago I had an idea to write an e-book about the 555 timer. That has now manifested itself into a full-blown print book, Kindle book, and a complete parts kit for the projects listed inside.

The Ultimate Beginner’s Guide to the 555 Timer: Build the Atari Punk Console and Other Breadboard Electronics Projects. Yes, it’s a mouthful, but it gets the entire scope of the book across in the title.

The book is available on Amazon here.

I also collaborated with Jameco to assemble a full parts kit with all of the components required to complete the projects listed in the book. The parts kit is available from Jameco here.

The official homepage for the book, which will include videos of each chapter and project in the book, plus much more, is here: bent-tronics.com/555-timer-circuit-book

Check out this video of me opening up the book and kit for the first time and a quick overview of each.

Here’s the Amazon blurb:
Unlock weird noises, hypnotic lights, and master the 555 timer.
Buy the print version of this book first to get the Kindle version for just $0.99! (not available in all countries)
This fast-paced, easy-to-follow book teaches you how the 555 timer works with step-by-step instructions and hands-on projects. Whether you are an electronics enthusiast or a beginner, this DIY guide shares simple tricks and hacks to put the 555 timer into action. FULL-COLOR illustrations show you how to transform circuit schematics into real-world working examples on a standard breadboard – no soldering required! High-resolution oscilloscope screenshots reveal detailed views of complex waveforms not able to be seen with the human eye. Advance your skills by completing the included projects so that you can create your own unique designs. A complete parts kit is available too!
You will learn how to:

• Use a breadboard
• Utilize the 555’s pins
• Trigger “one-shot” mode
• Blink an LED
• Generate noises with an oscillator
• Create a frequency divider
• Make a bistable flip-flop
• Source and sink current
• Build and understand the Atari Punk Console

The post My new book: The Ultimate Beginner’s Guide to the 555 Timer appeared first on Bent-Tronics.

Sometimes you just need to know if a MIDI controller is outputting anything. Even many high-end MIDI modules/boxes will have a “MIDI Activity” light, just to let you know something is being transmitted/received. That’s what I have made in this video.

Using a sacrificial MIDI cable, an LED, and a 220 Ohm resistor, you too can make this tester/activity light, probably in less than 10 minutes. Here is a rough wiring diagram.

There really isn’t too much critical about the parts used. MIDI devices use a 5 mA current loop at 31.25 Kbaud as part of their serial communication protocol. Most LEDs and a ~220 Ohm resistor will result very close in the neighborhood of 5 mA when used in this circuit. Devices with a MIDI input have basically this same thing as the LED, except in the form of an optoisolator IC.

If you don’t want to sacrifice a MIDI cable you currently own, cheap ones can be found here on Amazon, and here on eBay.

I’ll be exploring MIDI much more in-depth in future videos. Let me know in the comments below if you have any ideas/questions for future videos about MIDI.

The post Video: Make the World’s cheapest MIDI Tester appeared first on Bent-Tronics.

Have you ever wanted to plug in a professional studio mic to your iPod touch/iPhone? There may be a commercial solution, but I couldn’t find one. Even if there is one, I figured I could build one cheaper than a ready-made one. You could also use this for a line-in (my original reason for the project), but the source really needs to be taken down to mic level from line level for good sound quality.

The hardest part was finding the 3.5 mm 4 conductor plug (found it at Mouser, #171-7435-EX). The soldering to the plug was a bit tricky too. I needed a cable with at least 4 conductors inside, and I wanted to build this for next-to-nothing, so I used some CAT5 ethernet cable I had. CAT5 has 8 conductors, so if you know of any other common cable with at least 4, you can use that.

I’ve included a rough wiring diagram below.
***UPDATE: Thanks to PTM for pointing out the iPod/iPhone’s audio input is meant for an electret mic. Therefore, there is 2.7 v across the input. However, there is only a tiny bit of current. If this concerns you and you want to get in the habit of doing it the right way, you should put a 1 – 10 uF cap like this one in-line to block the dc. If you don’t know how or want to do this, the current probably won’t do any damage, but be warned.***

The sound quality with a Shure SM58 plugged into the iPod touch was way better than a very good pair of Shure earbuds/mic. When you look at the files in Sound Forge etc., the noise floor was about -60dB with the SM58 and about -50dB with the earbuds. The SM58 had way more dynamic range and obviously less background noise too. Not that surprising, since it’s a professional mic, but more proves that for serious recording, this is well worth doing.

The earbuds/mic aren’t terrible. It’s more a question of “how good” do you need to get? On a pair of normal home computer speakers, there may not be as much of a difference, but I’m listening through a $1400 pair of Event studio monitors.

Here are the sound files to compare. They were recorded with the free Griffin iTalk app at 44.1k and file transferred directly via wifi :

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A) In this method, each RCA jack is wired/soldered to an individual bend point on the circuit board. You then plug in RCA cables to the jacks to make each point-to-point connection.

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B) In this method, some of the RCA jacks are wired/soldered to bend points on the circuit board, and the rest of the jacks are jumpered to those. This allows for one bend point to be connected to more than one other bend point.

Here’s a combo, great for 1 to “X” bends – you get the idea…

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