New Projects You Can Build - Jed Margolin
I love making things. That is why I became an engineer. This way I can design the things I make. And I can make the things that I want.
If you are new to making things I have written a tutorial for you: www.jmargolin.com/making/jm_make1.htm
This is a very short summary:
A. Soldering
1. Wear protective glasses when you solder.
2. Use a temperature-controlled soldering iron. I use a temperature of 340 degrees Celsius for most things electronic. (For copper plumbing I use a propane torch.)
3. Keep the tip of the soldering iron clean and tinned. This is necessary to efficiently transfer the heat to the work. A dirty (oxidized) tip won’t transfer heat very well. Don’t use a damp sponge to clean the tip. The best way to clean the tip is to use 0000 steel wool.
4. Don’t inhale the fumes from soldering.
From: https://hackaday.com/2017/02/23/what-the-flux-how-does-solder-work-anyway/:
Electronic solder usually has a flux made of rosin. Rosin is a natural product derived from pine trees, notably the loblolly and longleaf pines for US-made rosin. It has the advantage of being more or less inert at room temperature but highly acidic when liquified, and has a melting point slightly lower than solder. The rosin core of electronic solder will therefore melt before the solder, flowing into and around the joint. The acidic liquid reacts with metal oxides, exposing clean metal for the solder to wet into. The acidic liquid flux converts the metal oxides to metal salts and water, which are typically locked up in the flux when it solidifies. The reaction products are generally harmless at that point, but some processes still require the used-up flux to be removed.
If you don’t have a fume hood use a fan to suck the fumes away from you.
5. After soldering a board clean the flux off of it. The recommended agent is isopropyl alcohol.
B. Desoldering
Sometimes you have to desolder a joint. For years I used solder braid or a manual desoldering pump. They don’t work very well.
The best way to unsolder a joint is where a vacuum pump (producing a continuous vacuum) sucks the solder through the heated soldering iron. They are expensive. The next best way is where a mechanically armed pump sucks the solder through the heated soldering iron. They cost a lot less but you have to keep arming and triggering the pump.
C. Making Things
1. Solderless breadboards. They suck.
2. Soldering wires point-to point. Very time consuming.
3. Wire Wrap. The easiest way to wire circuits other than using a PC Board. I am afraid Wire Wrapping is becoming a lost art.
4. Using a Printed Circuit Board. You can design your own. Like most things, the more you do it, the better you get at it. There are a number of good PCB Design programs that have free versions. (I use DipTrace.)
I am posting several of the projects I have done in the past several years. I am including the zipped Gerber files so you all you have to do is select a PCB fabricator and upload the zipped Gerber files to them.
D. Getting the boards fabricated.
This is a good Web site for finding board fabricators. https://pcbshopper.com/. You enter the size of the board and the number of boards that you want. It gives you the price and shipping options from a number of fabricators all over the world. It isn’t perfect. You have to go to the companies’ Web sites to get the exact prices. Well, you have to go to a company’s Web site anyway to order boards.
For the past several years I have ordered boards from these companies. They all make excellent boards.
ALLPCB: http://www.allpcb.com/ As I write this in January 2022 ALLPCB has a really great deal. You can get an order for FREE (including free shipping). You can’t beat free.
JLCPCB: https://jlcpcb.com/quote
PCBWAY: https://www.pcbway.com/ If you order boards from PCBWAY using the links I provide they will give me a small royalty.
E. Buying parts.
I frequently buy parts from eBay. But there are some parts that I have bought on eBay that have consistently been Bad Parts: TL062, TL064, TL082, TL084, ICL7660.
For these parts I recommend Tayda Electronics (www.taydaelectronics.com). They don’t sell everything but the parts they do sell are reasonably priced, their parts have always been good, and their shipping charges are reasonable.
For other things I use the standard distributors. All of them charge too much for shipping.
Digikey (https://www.digikey.com/)
Newark (https://www.newark.com/) Sometimes they have great prices on some MSP430G2xxx microcontroller. As I write this in January 2022 they are selling the MSP430G2302 for $0.55 . https://www.newark.com/texas-instruments/msp430g2302in20/microcontroller-mcu-16-bit-msp430/dp/24T4680?st=msp430g2
Mouser (https://www.mouser.com/) Their shipping charges are slightly lower than Digikey and Newark but their Web site is excruciatingly slow.
Here are the projects. If you value what I am teaching you and giving you, you can show your appreciation by sending me $5 using PayPal. To do this log into your PayPal account (www.paypal.com), find the Send button, and click on it. Then enter my email address (jm@jmargolin.com) and then the amount.
1. GPS Clock and Armageddon Alarm Jed Margolin 10/9/2021
A GPS Module using the U-blox NEO6MV2 is used to receive the GPS timing signals to show the exact time on a 16x2 LCD display.
In addition to the display, the end of each minute is signaled with a musical cord. To hear it Click Here.
It features an Armageddon Alarm Mode. I usually receive 11 or 12 GPS satellites. if the number of satellites drops to three or fewer something bad is happening. The odds that the GPS system is having a technical problem are vanishingly small.
What is happening is Armageddon.
Armageddon can happen in several ways:
a. A huge coronal mass ejection (CME) from the Sun that hits the Earth. The CME will burn out all of the satellites in orbit as well as the power grids (the Eastern Grid, the Western Grid, and the Texas Grid).
b. A Global Thermonuclear War. The first thing everyone will do when they start Armageddon is destroy or otherwise disable everyone else’s satellite navigation systems.
The GPS Clock With Armageddon Alarm will give you instant notice by playing this: Click Here. It also provides a 3.3V logic level signal that you can connect your own alarm to. (The interface depends on what your alarm is so you will have to do that yourself.)
You don’t have to be a Prepper to want to know when the World is Ending.
After I designed this project (and first posted it), from GPS World November 29, 2021:
The Kremlin warned it could blow up 32 GPS satellites with its new anti-satellite technology, ASAT, which it tested Nov. 15 on a retired Soviet Tselina-D satellite, according to numerous news reports.
Russia then claimed on state television that its new ASAT missiles could obliterate NATO satellites and “blind all their missiles, planes and ships, not to mention the ground forces,” said Russian Channel One TV host Dmitry Kiselyov, rendering the West’s GPS-guided missiles useless. “It means that if NATO crosses our red line, it risks losing all 32 of its GPS satellites at once.”
For the GPS Clock and Armageddon Alarm Click Here.
2. Audio Tone Burst Generator Jed Margolin 10/16/2021
The Audio Tone Burst Generator produces a periodic burst of tone at a User-selected audio frequency at a User-selected repetition rate. It can also be used as a regular audio generator. The frequency range is 20Hz to 10 KHz.
It is used for measuring the time delay of a piece of audio equipment. Modern audio equipment may use some fancy digital processing which may introduce a noticeable delay in the sound. You may want to measure the time delay in a piece of audio equipment in the following situations.
1. If you use your own sound system with your TV and your sound system does some fancy digital processing the delay may be long enough that you will notice that the actor’s mouth movements are not synchronized with the sound. That is very distracting. For television applications, the Advanced Television Systems Committee recommends that audio should lead video by no more than 15 milliseconds and audio should lag video by no more than 45 milliseconds. See https://en.wikipedia.org/wiki/Audio-to-video_synchronization
2. In a sound re-enforcement system such as may be used in a meeting, you can increase the feedback margin by several dB by using a frequency scaler (pitch changer) to change the sound going to the sound re-enforcement system (amplifier and speakers). The sound being fed back is at an ever increasing or decreasing frequency so it doesn’t howl. If you limit the frequency scaling to +/- 5% the people speaking will not notice. Indeed, you should lower the pitch of the person’s voice, not raise it. When we talk, bone-conduction to our ears acts as a low pass filter so our voice sounds lower to us than to the people we are talking to. Thus we are less likely to notice that our speech has been frequency scaled down a little.
The frequency scaler will have some time delay. If delay is more than 50ms we will hear that as an echo and most people will be distracted by that.
Indeed, if the delay is around 200ms most people will try to talk slower (and slower) in order to “catch up” with themselves. This can provide a great deal of amusement for everyone except the person who is talking. The amount of delay depends on several factors including age. See this article on Delayed Auditory Feedback (DAF): https://en.wikipedia.org/wiki/Delayed_Auditory_Feedback. A delay of 200ms seems to be the worst: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4477042/ .
For the Audio Tone Burst Generator Click Here.
3. Precision Low Frequency Signal Generator Jed Margolin 11/8/2021
The Precision Low Frequency Signal Generator produces a User-selected signal from 10Hz to 90Hz with 0.1Hz resolution for testing subwoofer speakers. The frequency is displayed on a 16x2 LCD. The sine wave is produced by stepping through a table of 64 values and sending them to the MCP4921, a 12-bit serial DAC that uses an SPI interface.
For the Precision Low Frequency Signal Generator Click Here.
4. Woof Meter Jed Margolin 11/8/2021
The Woof Meter is for testing subwoofer speakers to measure their Thiele-Small (TS) parameters. These parameters are necessary in order to properly design the speaker cabinet. Sometimes you might not have the TS parameters for a subwoofer speaker you want to use and sometimes the TS parameters provided by the speaker manufacturer are wrong.
To measure the TS parameters of a subwoofer you need a sensitive voltmeter with a good low frequency response. Your voltmeter might not have a low-frequency response that is good enough for testing subwoofers.
The Woof Meter contains a low frequency preamp, a precision full-wave rectifier, and a DC filter. It has a voltage output that can be read with any standard DC meter. It also has a current output for use with an analog 1mA meter.
The Woof Meter is a companion to the above Precision Low Frequency Signal Generator.
For the Woof Meter Click Here.
5. MyTX4 Jed Margolin 11/15/2021
I bought a La Crosse WS-9025U Weather Projection Station from Costco in October 2003 for $43.29 . It projects the time and outdoor temperature on the ceiling, which I like. It also receives WWVB to set the time. My WS-9025U spent its first two years in the mild climate of San Jose (California) and then 13 years in the Virginia City Highlands in Nevada where the temperatures can go from 0 degrees (F) in the Winter to 100 degrees (F) in the Summer.
Three years ago the outdoor sensor started eating batteries faster than it used to. Then I started getting an error message of OF.L for the outdoor temperature. That meant that the temperature/humidity sensor was bad. The transmitter part was still working but the data was bad.
La Crosse does not make the TX4U sensor anymore. For awhile they said to use the TX7U. Now their Web site doesn’t mention it at all. Besides, the TX7U Sensor cost too much ($28.65 on Amazon) and has gotten some bad reviews.
La Crosse doesn’t make the WS-9025U anymore either. Companies (including La Crosse) make new units that do projection but they get generally bad reviews. And they are ugly.
The sensing element in the TX4U is unknown so replacing it was not an option. So I made my own TX4U replacement using a Bosch BME-280 sensor and a HopeRF rfm69hw RF module..
For MyTX4 Click Here.
6. BME280 Tester Jed Margolin 11/29/2021
This project is for testing the Bosch BME280 sensor.
The BME280 sensor measures temperature, absolute air pressure and humidity. I use it in my project My TX4 Wireless Sensor Transmitter to replace the La Crosse TX4U wireless sensor which is no longer made.
When I started using the BME280 I discovered a problem. Several times when I have bought the BME280 on eBay the sellers have sent me the BMP280. The BMP280 measures temperature and absolute air pressure (no humidity). I also received some BME280 sensors that gave erroneous readings of the temperature and humidity. :-(
The definitive test is to read the part and display the values and the device ID. That is what the BME280 Tester is for.
I have also included the code to read the HTU21D Sensor by TE.
The board can also be used for developing the software for other sensors that use either the SPI or I2C interface.
For BME280 Tester Click Here.
Old Projects
7. Atari BattleZone Motor Sound (Coin-Op)
Atari’s BattleZone game is considered the first real 3D video game. I did the 3D graphics algorithms and the hardware sounds. This board produces the BattleZone Motor sound using the same circuit I designed for BattleZone except the engine speed is controlled by a pot instead of a single bit.
For BZ Motor Click Here.
Jed Margolin
Updated 1/10/2022