A throwback of sorts… The Buzzer Box!

Back when I was around 11, I strolled into a Radioshack and bought some wire, a buzzer, and a battery pack. I had a weird fascination with my elementary school’s fire alarm and wanted to recreate it. Completing the simple circuit by tapping wires together was enough to satisfy me until the project was lost. Fast forward about 15 years later, I’m revisiting the project that started it all.


This circuit is slightly more complicated than the original, I’d say. I used a 555 timer to get the pulse that would buzz the buzzer on and off at roughly a 50% duty cycle. In the end, I ended up using 9v instead of the original 5v I had planned, but it worked just the same.


The project was put into this small enclosure. I drilled a hole for the button that is pressed to activated the buzzer alarm.


Here’s the circuit on a breadboard to test and experiment before soldering the circuit permanently.


A close-up of the circuit on the perfboard.


A close-up of my soldering.


After soldering the components to the perfboard, I soldered the buzzer, battery, and switch into the circuit.


After some musical chairs with the components, and then some hot glue, everything was set into the enclosure.

Here’s the Buzzer Box in action…

It was a simple [and useless] project but I’m the kind of person that likes to revisit the past in ways like this.

Thanks for reading!




That might as well be the name of my “Wastebin Project” category. I haven’t done a Wastebin Project in a while so I’m shaking off the dust on this blog category today. This category is for those small random projects that only last for a day. They usually happen without proper thoughtful prototyping. It’s just about getting the creative juices flowing, experimenting, and having fun thinking on the fly.

Anyways, today I wanted to try something I’ve been meaning to do for a while, and that is try to create the smallest mobile robot I can. I also wanted to challenge myself to see what I could come up with in an hour.

I’ve done a couple of mobile robots before. My first robot was “Frank” who won the hearts of many. My second robot, “Greg”, was what I liked to call the Mobile Billboard because it was a rectangular bot with an LCD strapped to it. With my PCB designs that I’ve been posting about for the past little while, I can get a mobile robot to get into an even smaller form. Spoiler: It doesn’t work out, but seeing what doesn’t work along the way was interesting to me.IMG_20140924_154601This was it at the end of the project. If things did work out, I’d swap out the jumper wires for shorter soldered wires to neaten things up. What really was the final nail in the coffin was a wire between the 9v battery holder and my AMS1117 Voltage Regulator Board broke. But that was just one nail, among a few others.

The big thing I learned was that the servo library doesn’t work with the Attiny85 microcontroller because the servo library relies on 16-bit timers while the Attiny85 has 8-bit timers. I’ll have to look into it, but upon some light research it looks like it’s possible. After I realized that, I swapped out my Attiny85 Breakout Board with my Atmega328p Breakout Board. I got the servos rolling, but there was no control or logic behind it.

I wanted to try using a photoresistor instead of the ultrasonic sensor to be the eyes of the bot. I didn’t test the photoresistor so I couldn’t calibrate it. I was just guessing values but none of them worked so I don’t even know if the photoresistor was working at all. I still have the circuit so I can play around with it.

IMG_20140924_155017I kept the chassis because I want to try this again. This is how I always make my chassis but it’s a lot smaller compared to my previous robots.
IMG_20140924_155031This is the photo resistor circuit, as well as the power supply outputs (the headers) for the servos. I’ll play around with the photoresistor and maybe this could be back again in round two.

Thanks for reading! I’m still working out plans for my next project. It should be a light show… Stay tuned!

ATmega328p Breakout Test Results

In my last post, I talked about the tests I did with the AMS1117 Board. Now it’s over to the ATmega328p Breakout Board. The testing was a lot simpler, and included the AMS1117 board.IMG_20140919_121331This was it. The test was just to run a sketch on the ATmega328 microcontroller, uploaded using an Arduino Uno. The sketch was some patterns that used all 17 outputs (the 11 (not using RX or TX), plus the analog in pins used as digital outputs). The chasing patterns made sure that that the pads were connected in order. Here’s a video:

IMG_20140919_154612I used my multimeter to do some other tests. I tested the other pads on the board (RX/0, TX/1, and the Vcc and GND pads) with the multimeter. I also measured the curent flowing between the AMS1117 and the ATmega328 board. The reading in the picture above is from when all of the LEDs are on.

One thing I realized is that the 1A fuse for the uA and mA setting on my multimeter is blown. I went looking for them and the cheapest I can find is a 20 pack for ~$5… The A setting works just fine so I can live with it. The fuse on the A setting is 10A so it should last a while and would be the one I’m more willing to replace if it does blow someday.

Anyways, thanks for reading! I’m still planning out some projects so stay tuned!

AMS1117 Board Test Results

In my last post, I talked about assembling my two new PCB designs. In this post, I’ll talk about the results of some tests with the AMS1117 dual fixed voltage regulator board.

As I was assembling the board, I had realized that I hadn’t accounted for the voltage drop of the diode. It wouldn’t be an issue, except that  I wrote that the maximum drop out of the AMS1117 is 1.3v on the back of the board. Theoretically, there’s a dropout of 2v with the reverse polarity protection diode in the circuit, which is about the same dropout as the LM7805 voltage regulator. I’m glad I put in the diode though, since I’ve accidentally connected the battery backwards a few times already.

Anyways, I don’t have a variable voltage supply so I built an LM317 variable voltage regulator on a breadboard for this test. The test was to ramp up the voltage to see when the 3.3v and 5v outputs would appear so I can measure the dropout.IMG_20140919_101619

You can find my test notes here. Basically, I found that the total dropout with the diode for the 3.3v regulator to be 1.74v and 1.59v for the 5v regulator. I’d round up the total dropout for both to 1.9v, or 2v to make things easier. I chose the AMS1117 instead of the LM7805 because of the lower dropout, but I forgot about the protection diode. I’m still glad I went with it because it reduces the board size significantly, and the SMD soldering is fun.

Test results for the ATmega328p Breakout Board should be posted soon. It was a pretty basic test, which it passed. Yay.

Thanks for reading!

Attiny85 PCB Rev B Preview

Moving along with some revisions to my first two PCB designs, I’m working on some changes to the Attiny85 programmer & breakout board. The following is sort of a mock up as I’m just trying to figure out the form of the board right now.

1So the first thing that you’ll notice is that it’s not a square. It has rounded corners this time! But really, the form of the board has changed a lot. I want to design it so that you can break off the programming area when you’re ready to use the board in your project. The benefit to that is the breakout takes up less space in your project… and it’s kind of neat, IMO.

Something else I did new this time is that this board is actually completely manually routed. I’ve relied mostly on the autorouter up to this point. The Design Rule Check isn’t coming up with any errors so that’s positive.

Some parts should be coming in any day now that will let me assemble and sell the first version of the Attiny85 Programmer & Breakout on eBay, along with the other things I’m currently selling. People buying them will show me how much interest there is in this kind of thing. I really like this design I’m going for so hopefully there’s enough interest to get the new version manufactured when it’s ready (Rev A buyers may get a discount). Stay tuned! Thanks for visiting!

Back to PCBs

With the first fountain show complete, I’m taking some time to consider my next plans for it. I have a few ideas but I don’t have the motivation yet to go through with any of them. I feel like switching gears back to my PCB designs because I had projects going on that had stopped because of the fountain project.
2This is the next board that I’m working on sending out to get manufactured. The main design is the ASM1117 voltage regulator board because I’d like to try working with SMT parts again. I already bought the ASM1117 regulators so I kind of have to get this board made eventually. I’m just a little worried that they won’t work like the shift register boards. I’m still trying to figure that out…

The other design is an Atmega328p breakout. Pretty straight forward.

I hope to send this board out by the end of the week to get made.

AMS1117 + Atmega328p PCB update

combinedI’ve combined the two designs I was working on. The top is the Atmega328p breakout and the bottom is the ASM1117 voltage regulator that outputs 5v and 3.3v. I ordered some parts for this board as there is a sale on at Dipmicro. I’m excited to try SMT soldering with my iron. I need to do some last minute checks on the board to make sure the connections are correct. I’m also waiting for my first boards to come in so I can make adjustments based on those if necessary.

This board includes some things I don’t think I did right in my first PCB. The board has rounded corners, which is not really fixing a problem but it is something new I’m trying. I also went with a small tab between the two boards with some small drilled holes to help make the break a little easier. I’m not sure how the first boards are going to turn out but I’m fairly certain the slot I made in it is not going to be what I was hoping for. Anyways, the last thing is that I didn’t make the top and bottom layers that cover the board part of the ground plane. I’m not sure if that’s really a mistake or not but I know it does help manufacture the board faster (instead of scrapping off everything but the traces) and takes away some traces, as well as some good electrical side effects like helping with interference and noise.

I will be receiving the parts for the boards in this post so expect a mailbag post soon!