A simple 8-channel receiver voting controller for enhanced repeater coverage and usability

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KA7OEI has written an article detailing a simple 8-channel receiver voting controller:

To simplify things, this voting controller sits in “front” of an ordinary repeater controller, taking the audio and COS inputs from the various receivers and outputting a single audio and COS signal.
If the repeater system in question uses subaudible tones, it is recommended that “discriminator” audio (e.g. that which has not been de-emphasized) that has not been subject to a squelch or tone detector audio gate be applied to the voting controller from the link receivers as well as any “local” receivers as this will assure that the voted audio will contain the subaudible tone.

More details on KA7OEI ‘s blog.

Mostly PIC16C57

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CAPS0ff team posted an article taking a closer look at 8 “PIC16C57s”:

We were recently sent 8 “PIC16C57s” from:

*High Seas Havoc (403/C013)
*Wargods (U69, C020)
*MACE (U96, C021)
*Carnevil (U96, C022)
*BioFreaks (C023)
*Gauntlet Dark Legacy (C024)
*Gauntlet (U37, C025)
*Blitz 99 (U96, C026)

More details at CAPS0ff blog.

6 channel speaker selector

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Dilshan Jayakody published a new build:

If you are an audio enthusiast and if you have multiple audio systems and speakers, you may definitely need to have a speaker selector switch. These switches allow you to route a audio signal through a switching system and distribute it to various speakers. Using this listener can select single amplifier – speaker combination through the switch. We mainly design this switch to share our speaker system with multiple audio amplifiers. We design this switch to handle 6 stereo audio channels.

See the full post on his blog here.  Project files are available at Github.

Building a giant USB three key mechanical keyboard

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Glen Akins shares his latest build the giant three key USB keyboard:

After seeing this giant mechanical keyboard at Adafruit, I decided I had to build my own. Adafruit made theirs out of wood and used one of their Python-compatible microcontroller boards. I wanted a sloped top on my keyboard. I also wanted to check out what was new with Microchip’s USB device stack. I decided to build my keyboard out of aluminum and use a PIC18 microcontroller.

See the full post on his blog here, Photons, Electrons, and Dirt.

PIC18 four-channel DMX relay controller

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Glen Akins has a nice build log on his four channel DMX-controlled relay, that is available on GitHub:

 Halloween was right around the corner and I needed a timer with a bunch of relays to trigger some store-bought props and a fog machine periodically. (Mental note: read fog machine specs carefully—not all come with timer remotes.) My first thought was an Arduino and cheap relay board. Second thought was to build something with a micro and some relays. Third thought was that if I’m going to build something, might as well add DMX and package it up into a neat enclosure. Hence, the four channel DMX-controlled relay project was born.

See the full post on his blog.

PICKit 3 Mini

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Reviahh has published a new build, the PICKit 3 Mini:

Previously, I made a Pickit 3 clone – (see previous blog post). It works well, but I have often wondered just how little of its circuitry was needed to program and debug the boards I make. For instance – I primarily use the newer 3.3V PIC32 processors, so I really don’t need the ability to alter the voltage like the standard Pickit 3 can. I also have no real need for programming on the go, or even to provide power to the target MCU to program. Knowing this – I decided to see what I could do to remove the circuitry I didn’t need, yet still have a functioning programmer/debugger.

See the full post at DIY PCB homepage.

RX/TX sequencer

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Lukas Fässler has designed and built an RX/TX sequencer based on a PIC16F18325,  that is available on github:

Much like the beacon keyer presented here earlier, this RX/TX sequencer is a simple but useful little device. Its typical use is in ham radio applications when a separate power amplifier (PA) and/or a sensitive low-noise pre-amplifier (LNA) is used. Care has then to be take to safely transition between RX and TX states – and that’s where this sequencer comes in.

Project info at Soldernerd homepage.

Check out the video after the break.

Beacon Keyer

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Lukas Fässler from Soldernerd published a project writeup showing how he built a PIC-based beacon keyer:

This is likely the first ham radio related project that I document here on this blog
But my very first PIC project was a beacon keyer that I made for my father, HB9BBD. That was in 2013. A beacon keyer is a great project to get started with microcontrollers since it’s not much more than a fancy way of blinking an LED.

Project info at Soldernerd homepage and the GitHub repository here.

Light Dimmer Shows How to Steal Power from AC Line

We see a lot of traffic on the tips line with projects that cover old ground but do so in an instructive way, giving us insight into the basics of electronics. Sure, commercial versions of this IR-controlled light dimmer have been available for decades. But seeing how one works might just help you design your Next Big Thing.

Like many electronic controls, the previous version of this hack required a connection to a neutral in addition to the hot. This version of the circuit relies on passing a small current through the light bulb the dimmer controls to avoid that extra connection. This design limits application to resistive loads like incandescent bulbs. But it’s still a cool circuit, and [Muris] goes into great detail explaining how it works.

We think the neatest bit is the power supply that actually shorts itself out to turn on the load. A PIC controls a triac connected across the supply by monitoring power line zero-crossing. The PIC controls dimming by delaying the time the triac fires, which trims the peaks off of the AC waveform. The PIC is powered by a large capacitor while the triac is conducting, preventing it from resetting until the circuit can start stealing power again. Pretty clever stuff, and a nice PCB design to boot.

Given the pace of technological and cultural change, it might be that [Muris]’ dimmer is already largely obsolete since it won’t work with CFLs or LEDs. But we can see other applications for non-switched mode transformerless power supplies. And then again, we reported on [Muris]’s original dimmer back in 2009, so the basic design has staying power.


Filed under: home hacks, misc hacks