Since this design derived from Palm Arduino, I will called it Palm Arduino II.
This Palm Arduino, the Second, will be the combination of Palm Arduino and Portable 5V Voltage Regulator.
So that everything is staying together closely in the same package!
Palm Arduino II will be a little smaller, 1-3/8" wide x 2-3/8" x 1/2" thick (Palm Arduino the First are 1-1/2" wide x 2-1/2" long x 1/2" thick), so it will be fit on the back of the 9V battery holder.
Palm Arduino II will be powered by separate PCB installed on top of 9V battery holder that has both 5V and 3.3V regulator.
Palm Arduino II
Parts for Palm Arduino II are exactly the same as Palm Arduino, less 3mm Green LED and 1K Resistor.
I changed the nuts and screws size to 4-40 instead of 2-56.
1 no. ATMega328P with Arduino Bootloader
1 no. 10K Resistor
1 no. 16Khz Resonator
2 nos. 0.1uF Capacitor
1 no. 1x6 Male Header
1 no. 1x14 Female Receptacle
1 no. 1x4 Female Receptacle
1 no. 1x6 Female Receptacle
1 no. 1.375" wide x 2.375" long, 1/8" thick clear Acrylic sheet
Some hookup wires
2 nos. 4-40 Flat-Head Machine Screws
4 nos. 4-40 Steel Machine Hex Nuts
Voltage Regulators PCB
1 no. Slide switch
1 no. 1N4001 Diode
2 nos. 100uF Electrolytic capacitor
1 no. 10uF Electrolytic capacitor
1 no. 0.1uF Capacitor
1 no. 78L05 Voltage Regulator, TO-92 package
1 no. 78L33 Voltage Regulator, TO-92 package
1 no. PCB about 7/8" wide x 1" long
2-pin Female socket with hookup wire