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Problems and Distractions
I haven't been able to post in quite a while - far too many things in real life distracting me. But now that I have gotten back to hobby time, I am expanding my system with an I2C interfaced GPIO...
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Gotta Know When to Fold 'em
For the past few months, I have burned up a lot of hobby time trying to build an interface to control the Orbit 58874 sprinkler control valve. These simply connect in-line with standard water hose...
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Pulse Width Motor Control
My last project had me digging through old robotics parts to find an H-Bridge Motor Controller. I found one that had several TTL chips on the circuit as well and it reminded me of a trick some of you...
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Running From an External Hard Drive
The SD card of the Raspberry Pi is required for booting. While you may not be able to boot from an external hard drive, moving the / partition there will significantly speed up the Raspberry Pi....
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Solid State Relays
I find solid state relays (SSR) very convenient, especially for controlling AC power lines. They typically include opto-isolation and zero crossing detection (explained later.) Also, they can be...
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Fail-Safe Circuit Using Discrete Logic Chips
When controlling a device that can present a danger to people or property, it is important to include adequate safeguards, in both software and hardware. I now have a Raspberry Pi controlling the...
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Interface to Wireless Driveway Sensor
I have a driveway that is over 300 feet long and it is nice to have some advance notice that someone is driving or walking in. Previously, I have used a very expensive IR beam-break detector. It gave...
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Stupid Simple Tip #1
A rubber band and a pair of pliers make an quick and easy clamp for holding components while soldering.
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Stupid Simple Tip #2
The body of an old ball point pen can be easily made into a standoff of any size. And it's hard to beat the price.
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Stupid Simple Tip #3
The ribbon cable connector used for floppy disk drives on PCs can be used as a GPIO connector.They are larger than than the Pi GPIO connector (34 vs 26 pins) so they overlap some. These are cheap...
View ArticleStepper Motors
Stepper motors are unlike ordinary motors. A simple motor will spin when current is applied to the coils. Reverse the polarity of the current, and the motor spins in the opposite direction. Stepper...
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Server Box with Utilization Displays
A while back I built a server with the system root moved to an external hard drive.Blog Post - Running From an External Hard DriveThat system has now failed. I shouldn't be surprised since it was built...
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Stupid Simple Tip #4
Murphy was an optimist. I have repeatedly had problems with USB cables. USB cables are held in place only by the friction of the connector. Repeated insertions and removals WILL wear out a USB...
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Automated Home Brewing
Brewing Controller User InterfaceI have been a “home brewer” in the electronic hobbyist sense for decades, but I am also a “home brewer” of beer. I mentioned this in my post on Reading Temperature...
View ArticleCPU and I/O Utilization Display - Details
In the post Server Box With Utilization Displays I showed a system which displays CPU and I/O utilization in real time. If you are using the Raspberry Pi in GUI mode, then there are numerous tools to...
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Schematic for Analog Interface
A commenter asked for the schematic of the analog interface I made using an MPC3008. I seldom include schematics with my posts for several reasons. I don’t expect anyone to duplicate exactly what I...
View ArticleInterface to the Internet of Things with SkyNet
The Internet of Things (IoT) refers to the many servers that store data uploaded from various devices (things) connected to the Internet, which can range from weather stations, to home appliances, or a...
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Flame Sensor Update
This is a follow up to the post on Automated Home Brewing. There were several good ideas in the comments to that post about how to create a flame sensor. Some require an analog input, which I...
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Improved Home Brewing Controller
This post is an update to my Automated Home Brewing post. See that post for more details on the project. After adding some new features haphazardly, I had an ugly conglomeration of old and new parts....
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Debouncing GPIO Input
Reading the state of a GPIO pin is very simple. There are several methods to do this. But what if you need to detect a very short pulse on a GPIO line or you need to respond very quickly to a state...
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