Shared Projects by SmittyHalibut

A simple RF Lowpass Filter. Component values are dependent on your filter requirements.

This board will work as either Butterworth filter (eg: http://www.calculatoredge.com/electronics/bw%20pi%20low%20pass.htm) or Chebyshev filter (eg: http://www.calculatoredge.com/electronics/ch%20pi%20low%20pass.htm). Put in your cut-off frequency, impedance is probably 50 ohms, and 9 components. (For Chebyshev, you’ll also need to specify the pass-band ripple tolerances.) Then click Calculate, and those are your component values.

This board will take either 1206 SMT capacitors, or .1" radial capacitors. It’s laid out assuming FT37-43 toroids for the inductors, but will probably work with axial pre-made inductors too, they just won’t lay flat on the board. The SMA connectors will take either vertical or edge mounted SMA connectors.

A simple RF Bandpass Filter. Component values are dependent on your filter requirements.

This board will work with many Bandpass filter designs, such as https://www.electronicproducts.com/Bandpass_Filter_Design_Calculator.aspx . Put in your cut-off frequency, impedance is probably 50 ohms, and 5 L/C pairs. Then click Calculate, and those are your component values.

This board will take either 1206 SMT capacitors, or .1" radial capacitors. It’s laid out assuming FT37-43 toroids for the inductors, but will probably work with axial pre-made inductors too, they just won’t lay flat on the board. The SMA connectors will take either vertical or edge mounted SMA connectors.

A simple RF Highpass Filter. Component values are dependent on your filter requirements. I made this as an AM broadcast band blocker, cut-off at 1.7MHz. But you can put whatever values you want on it.

This board will work as either Butterworth filter (eg: http://www.calculatoredge.com/electronics/bw%20tee%20high%20pass.htm) or Chebyshev filter (eg: http://www.calculatoredge.com/electronics/ch%20tee%20high%20pass.htm). Put in your cut-off frequency, impedance is probably 50 ohms, and 9 components. (For Chebyshev, you’ll also need to specify the pass-band ripple tolerances.) Then click Calculate, and those are your component values.

This board will take either 1206 SMT capacitors, or .1" radial capacitors. It’s laid out assuming FT37-43 toroids for the inductors, but will probably work with axial pre-made inductors too, they just won’t lay flat on the board. The SMA connectors will take either vertical or edge mounted SMA connectors.

Test board for TL7700 based Pop Stopper.

Connect the ¼" to your headphones, and the 1/8" to your amp. The amp will see the two 150ohm resistors on the bottom on the board instead of your headphones for the first two-ish seconds after power on, so the POP of amp startup goes into the resistors, not your headphones. Similarly, on amp shut-down, it disconnects the headphones as quickly as it can before the shut-down pop hits your ‘phones.

Components on the board are labeled by value. None of the components pass audio (only the connectors and relay), so they can be of common low precision, nothing special, junk drawer quality.

The SOIC is a Texas Instruments TL7700 Reset controller: http://www.ti.com/product/TL7700 Note that the outline on the board is too narrow (my bad, sorry). I had to fold the pins under the chip to solder it to the board.

¼" connector is Neutek NRJ6HF, something like: http://www.mouser.com/ProductDetail/REAN/NRJ6HF-AU

Relay is HK19F type, like: http://www.ebay.com/itm/381374965631

A USB “keyboard” with just the Media keys. Really, you can program it for any keys you want, but I built it for the media keys my keyboard doesn’t have.

• Buttons are PCB mount Cherry MX switches, of your favorite color. I like Browns
• You’ll probably also want some key caps. This kit includes several options for media keys.
• The rotary encoder is also a pretty common part, but here’s an example.
• Microcontroller is an SparkFun Pro Micro
• The socket is a 24 pin “wide” socket, with the pins bent out so they can be soldered surface mount. It’s easier with the cheaper sockets rather than the really nice machined pin sockets.
• Buttons are pretty standard SMD 6x3x4.3mm buttons, for example.
• Passives are all standard 1206 bits, as marked on the board. Nothing is critical, 5% resistors and 10% caps are fine. Use your cheap crap here, not your good 1% components.
  • I’m realizing I didn’t label the bypass caps next to the WS2812Bs. They’re all .1uF, like all the other caps on the board.
• The LEDs in the Cherries and immediately on either side of the rotary encoder are standard 3mm LEDs of your favorite color.
• The RGB LEDs on the “controls” side of the board are WS2812B (The Adafruit link provided are SK6812, but they’re compatible.)
• The board is sized to fit in my favorite cheap plastic project case. Having said that, I think I’m going to make a laser cut wooden panel to sandwich the PCB with stand-offs. I’ll post a link here when I’ve done something.