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Archive for the ‘transmitter’ Category

In the world of ham radio, a “Fox Hunt” is a game where participants are tasked with finding a hidden transmitter through direction finding. Naturally, the game is more challenging when you’re on the hunt for something small and obscure, so the ideal candidate is a small automated beacon that can be tucked away someplace inconspicuous. Of course, cheap is also preferable so you don’t go broke trying to put a game together.

As you might expect, there’s no shortage of kits and turn-key transmitters that you can buy, but [WhisleyTangoHotel] wanted to come up with something that could be put together cheaply and easily from hardware the average ham or hacker might already have laying around. The end result is a very capable “fox” that can be built in just a few minutes at a surprisingly low cost. He cautions that you’ll need a ham license to legally use this gadget, but we imagine most people familiar with this particular pastime will already have the necessary credentials.

The heart of this build is one of the fairly capable, but perhaps more importantly, incredibly cheap Baofeng handheld radios. These little gadgets are likely familiar to the average Hackaday reader, as we discussed their dubious legal status not so long ago. At the moment they are still readily available though, so if you need a second (or third…), you might want to pull the trigger sooner rather than later.

At any rate, in the setup that [WhisleyTangoHotel] has outlined, the Baofeng radio is connected up to an MP3 player which is loaded up with a recording of your message and FCC callsign that plays in a loop. An Arduino and a relay module are then used to key the transmitter automatically by grounding out the microphone connector. As it so happens, the lanyard mount on the Baofeng is a convenient ground point and allows you to hook the whole thing up quickly with alligator clips.

If you’re looking for something a little more compact, we’ve previously covered a very nice wearable transmitter which can be used for fox hunting. We’ve even seen a gutted FRS radio stuck into a rocket if you want to take your hunt to the next level.



Reflow toaster oven using an Arduino

arduino, Oven, Reflow, RF, servo, transmitter Commenti disabilitati su Reflow toaster oven using an Arduino 

Ray Wang writes:

Hi, I recently built a reflow toaster oven using an Arduino. I know it’s pretty standard stuff, but my version has an automatic oven door opener (using a servo) and circulation fan to speed up the cooling time, and remote notification using an RF transmitter


Reflow toaster oven using an Arduino - [Link]


Arduino capture of 4 channels from an HK 6CH RX and an HK-T6A-V2 transmitter

arduino, capture PPM, HK 6CH, HK-T6A-V2, RX, transmitter Commenti disabilitati su Arduino capture of 4 channels from an HK 6CH RX and an HK-T6A-V2 transmitter 

Cattermaran controller water cooling control trim control and throttle up ramp to reduce stress on the drive train, and reduce battery drain from harsh acceleration burning up Amps because of Inertia.

Motor current measured with this device

The Arduino

Wired like this

Arduino nano captures 4 channels from an HK 6CH RX and an HK-T6A-V2 transmitter. Simplest code I could write

Very simple bit of code no interrupts just pulseIn() and noInterrupts() and the servos don't jitter any more than they do on the RX directly.  If you want to hack the RX have a  look here this guy seems to have a plan.

There is a wee mix on ch5 pot and elevator done in the code so the pot sets the base trim and the elevator lets you adjust the trim quickly.  Will be adding a RTC and a DC water pump on a 20A Turnigy brushed ESC for cooling control. If that goes well may use a hall effect device to monitor current and see if I can implement torque control with overspeed limiting, I think torque control will reduce shock loads when the prop looses grip in the surf.

This is the sketch as maidened with a throttle limit on one of the aux pots 

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