These are the bare board versions of a number of products that I'm selling here. They're gathered here since they can't be an option on the product pages, because bare boards are cheaper to ship than assembled ones, and Tindie does not allow you to make the shipping price depend on an option.

SOT-23 MOSFET breakout board ($1/six)

Assembled version

Simple SOT-23 mosfet (or anything else) breakout boards. Pads provided for a 1206 pulldown resistor. Sold in panels of 6 as shown. The boards can be easily separated by hand before or after soldering down the parts.

Improved SOT-23/SOT-89 Breakout Board ($2/12-pack)

These are the new and improved version of the above SOT-23 breakout boards. In addition to the improved silkscreen, these have wider traces for improved current handling, and pads for an SOT-89 package on the back. As with the original version, pads provided for a 1206 pulldown resistor. Sold in panels of 12 as shown. The boards can be easily separated by hand before or after soldering down the parts.

AMC7140 Breakout Board ($1/ea)

The AMC7140 is a low cost linear constant current regulator for driving high power LEDs at current of up to 500 or 800mA (chip is available in two versions, actual current is set by external resistor). As this is a linear device, you must take the power dissipation into consideration, particularly at high current and/or where the AMC7140 needs to drop a lot of voltage. Although these are less efficient than a switching regulator, the parts are inexpensive, and produce less noise, both electronic and acoustic (many switching regulators produce a humming or squealing noise under certain operating conditions)

Required parts (not included):

• AMC7140
• 2 1206 resistors for setting current - OR -
• 1 1206 resistor and 1 EVM-series digital potentiometer (1k, 2k, or 5k is likely appropriate, depending on required current)
• 1206 0.1uf cap (C3)
• 1206 capacitor for filtering (if application requires additional supply filtering)
• (optional) Two 2-pin 0.2" pitch screw terminals

AMC7135 Breakout Board ($1/4-pack)

The AMC7135 is a low cost linear constant current regulator for driving high power LEDs at a fixed current of 350mA. As this is a linear device, you must take the power dissipation into consideration - as the current is fixed, this is a function only of the voltage being dropped in the regulator. These devices are capable of operating with an amazingly low dropout of 0.2v or less.

Out of the box, the AMC7135 specifies a maximum input voltage of 6v - this is inconvenient in many cases, as there are many 350mA COB led arrays on the market which run at a voltage of 10V or more. However, a crude voltage regulator with a resistor and zener diode allows us to supply the Vcc pin of the AMC7135 with a voltage within it's operating range - and this works (though one must be particularly careful about power dissipation). These tiny boards provide the pads for such a zener diode and resistor, and have been used successfully in my projects to power 350mA COB leds running at 10-24v.

Required parts (not included):

• AMC7135
• 1206 0-ohm resistor (other low values will work) if using <6v supply OR
• 1206 470~1k ohm resistor and SOD-123 / MELF zener diode 3.3v to 5.1v if using >6v supply.

3W RGB LED / 4W RGBW LED breakout board ($1/2-pack)

Two-pack of simple breakout boards as shown for high power RGB and RGBW LEDs. These boards, being made on standard PCB material, do not provide the heatsinking that an aluminum base board does. While effort has been made to maximize the thermal dissipation of the PCB, it is definitely not suitable for 100% duty cycles, though they work fine at lower duty cycles.

AT24 EEPROM DIP to SOIC 8:1 splitter ($1/ea)

This board allows you to connect as few as 1, or as many as 8 AT24-series or compatible I2C EEPROM chips to a DIP socket intended for a single EEPROM.

Note that this does not provide any interfacing logic - the device these are being used with must be programmed appropriately to use them; this just makes it easy to connect them and expand an earlier hardware design. The chips need not all be the same. For example, if you've finished a design, and then realize you need to rewrite some data too frequently to use an EEPROM, you can use one of these to connect an EEPROM plus one of the pin compatible FRAM chips to the same DIP socket.

The address lines from the DIP outline are not connected - each SOIC outline has the address pins hardwired to a specific address (corresponding to the number next to the component, ie, the one marked U0 will have A0~2 low, hence address will be 0x50, the one marked U5 will have A2 and A0 high, so the address will be 0x55, etc). WP line is held low to enable write on all chips - if this is not desired, you can choose not to solder the WP pin, and bend it away from the board to disconnect it.

Required parts (not included):

• 1~8 AT24-series or compatible I2C EEPROMs, SOIC-8
• 1~8 1206 0.1uf ceramic capacitors (decoupling)
• 2 1x4 0.1" pitch machined pin header (normal pin header will work with some, but not all, DIP sockets, and may mangle the socket)
• 2 1206 I2C pullup resistors (if needed - typically, whatever you're plugging this into will already have them)

WS2811/1206 LED board ($1/ two-pack)

This is a 2" long lighting board that allows the WS2811 to be used to control a number of discrete LEDs. This is well suited for applications such as indicator LEDs (allowing as many LEDs as you need to be controlled with a single pin) or for decorative lighting where colors other than red, green, and blue are needed - for example, a single-color Larson scanner, or whites of different color temperatures (a comfortable warm white is difficult to get from RGB leds).

On the rear, install 3 WS2811 individually addressable LED chips in SOP-8 package, along with ~100 ohm resistors and 0.1uf capacitors (for decoupling). On the front, install 9 1206 LEDs (or other LEDs that can take 20mA and be made to fit on the pads).

IN and OUT markings are BACKWARDS due to a design error.

Required parts (not included):

• 3x WS2811 LED driver
• 3x 1206 ~100 ohm resistor (decoupling as recommended by datasheet)
• 3x 1206 0.1uf capacitors (decoupling as recommended by datasheet)
• 9x 1206 LEDs of your choice

6-channel AMC7140 driver for high power LEDs ($2)

This board is designed to mount a high power 4~6 color LED. The specific LED it was designed for is a 12W RGBWYV LED, but the 4 and 5 color LED beads can also be used. It has pads for 6 AMC7140 linear constant current LED drivers, decoupling capacitors, and current setting resistor(s). Enable lines are brought out to the header at the bottom. Required parts (not included):

• 4~6 channel LED bead
• 4~6x AMC7140
• 4~6x 1206 0.1uf capacitors
• 4~6x 1206 current setting resistors - may use one or two in series using provided pads

CH340G serial adapter, bare (Panel of 4 for $2)

Special deal Buy all remaining stock, get the polyimide stencil free.

CH340G serial adapter boards as used in my CH340G serial adapters.

• X1 is 12mhz crystal, 18pf, in HC49 package.
• LED1 and LED2 are 1206 LEDs, your choice of colors (for TX/RX lights)
• R1 and R2 are current limiting resistors for those LEDs - I use 2.2k, but anything from 1k to 4.7k should be fine, depending on how bright you want the LEDs to be. This can be either a pair of 0603 resistors or a 2-element 606 array.
• C1, C2 0805 18pf ceramic caps
• C5 - 0.01uf 0603 ceramic cap
• C4 - 0.1uf 1206 ceramic cap
• C3 - 1uf 0603 ceramic cap
• C6 - 1uf 0603 ceramic cap if assembling for 3.3v use.
• IC1 - 3.3v LDO regulator (if assembling for 3.3v use). The group of 3 pads in the corner selects 5v or 3.3v operation - for 5v, install a jumper or PTC fuse between the two pads closest to the corner. For 3.3v, install a jumper from the middle pad to the one further from the corner (as well as the regulator and capacitor as noted above.