Risa Uke

Size 18.3“ x 4.3“ x 1.2” (46.5 cm x 11 cm x 3 cm)
Scale length 14.2” (363.5 mm)
Tuning G-C-E-A or A-D-F#-B
Strings RISA Fluoro-Carbon
Finish Satin clear coat
Frets 14
Neck Maple, width 1.38“ (35 mm) at zero fret
Solid maple body
Fingerboard One-piece (neck, body, fingerboard)
Pickup Passive Shadow Piezo
Tuners 1:4, Banjo style
Weight 14 ounces 380 g

OTHER:

MANDOLINS
scale length: 13 7/8"
width of nut: 1 5/32"
width at 12th: 1 15/32"
strings, outside to outside, at bridge: 1 19/32"
highest fret: 21
depth of neck at 1st fret: 13/16"
depth of neck at 8th fret: 15/16"
length of peghead: 7 1/2"
depth of sides only: 1 9/16"
width of lower bout: 10 1/32"
length of body: almost 14" with scroll
max height of arch, top: usually 3/8"+*
height of bridge: 13/16"
max height of arch, back: usually 1/2"+
soundhole dimensions: 4 9/16" long
hypothetical bridge point to tail: 6 3/8"

from http://smart-instruments.com/gal95.html

constant current source

http://talkingelectronics.com/projects/200TrCcts/200TrCcts.html

TDA7052 w DC vol control

http://freecircuitdiagram.com/2010/10/09/btl-mono-amplifier-with-dc-volume-control/



This is BTL (bridged tied load) mono amplifier with DC volume Control circuit. This circuit uses TDA7052A/AT that is suitable not only for monitors and TV but also battery fed portable radios and recorders. The difference between conventional DC volume circuits and TDA7052A/AT the DC volume control is there is no coupling capacitor is needed in TDA7052A/AT the DC volume control to maintain the low offset voltage. Besides that, the TDA7052A/AT the DC volume control require low supply. The advantages of BTL principle are it has the ripple’s frequency on the supply voltage is twice the signal frequency and the supply current peak is lower.

3.6v charging

http://electronicsprojects.mediadir.in/nicd-battery-charger-with-reverse-polarity-protection/

Small and portable unit, Can charge multiple batteries at once

This NiCd battery Charger can charge up to 7 NiCd batteries connected in series. This number can be increased if the power supply is increased with 1.65V for each supplementary battery. If Q2 is mounted on a proper heatsink, the input voltage can be increased at a maximum of 25V. Unlike most of comercial NiCd chargers available on the market, this charger has a reverse polarity protection. Another great quality is that it does not discharge the battery if the charger is disconnected from the power supply.

Usually , NiCd batteries must be charged in 14 hours at a charging current equal with a tenth percent from battery capacity. For example, a 500 mAh is charged at 50 mA for 14 hours. If the charging current is too high this will damage the battery. The level of charging current is controlled with P1 between 0 mA – 1000 mA. Q1 is opened when the NiCd battery is connected with the right polarity or if the output terminals are empty. Q2 must be mounted on a heatsink. If you cannot obtain a BD679, then replace it with any NPN medium power Darlington transistor having the output parameters at 30V and 2A. By lowering R3 value the maximum output current can be increased up to 1A.

P1 = 1K
R1 = 680R
R2 = 47K
R3 = 1R-3W
Q1 = BC557
Q2 = BD679 (Darlington)
D1-D5 = 1N4148
D6 = 1N4001