Shared Projects by SmittyHalibut

For when you need to switch the positive side of your load (common cathode) instead of the negative side (common anode). Most FET shields use N-Channel MOSFETs which switch the ground connection, assuming the positive connection is always connected to power. This shield uses P-Channel MOSFETs which switch the positive, so it’ll work with loads that have a common ground (like this aquarium light )

The input is designed to take a PCB mounted Anderson PowerPole connector, but you can solder wires directly to it just as easily.

Components are as labeled on the board:

• FQP27P06
• BSS138
• 10k 1206 SMT resistor (take your pick)
• 1N4148 or any other rectifying diode. It’s just there to prevent the Arduino from trying to feed power to a potentially large load hanging off the MOSFETs.

Connects between your computer, your desk phone “headset” port, and something like a gaming headset with headphones and a mic. Mixes the telephone audio with the Line Out from your computer then sends it through a good headphone amplifier to your headphones. Similarly, the mic on your headset is amplified as necessar y and sent to both your telephone and your computer’s Line In port. One headset , two functions. Workplace Nirvana.

A 4MHz offset attenuator for radio direction finding.

Mostly based off this design with a few modifications:

• 3 position switch: Off, On (10db pad bypassed), and On with 10db pad.
• Better filtering LPF from 4MHz oscilator to mixer section, an LC instead of RC (replaced 100ohm resistor with 15uH inductor.) Should leak less RF.

The board is designed to fit into a ½" conduit pass-through box, like what you might put on the handle end of a measuring tape yagi (Google it; there are MANY plans and designs for them.)

Only parts that are “special” are:

• 2P3T Rotary Switch
• 15uH Inductor
• 10k Pot
• 4MHz Oscillator
• 5vDC TO-97 Regulator

The rest are just standard cheap-o resistors, capacitors and 1N4148 diodes, with values as labeled on the board.

Easiest way to get a hold of me is probably on Twitter: @SmittyHalibut. Shoot me a note with your experiences if you use this board! Thanks!