Notes on the Ruby guitar amp

Happy New Year!

I fool around with cigar-box guitars. I have also built two amplifiers for the guitars. The amps are built from the Ruby design at On the off chance that you might want to build this amp from parts at Fry’s, here’s a list of the Fry’s part numbers that correspond to the Ruby parts list, along with some comments.

Part Number Description Manuf Fry’s Number Price Comments
C1 100 uF Electrolytic NTE VHT100M25 $1.02 Hi-Temp
C2 47 nf NTE CML473K100 $0.59 0.047uF 100v
C3 100 nf NTE MLR104K50 $0.80 .1uF
C4 220 uF Electrolytic NTE VHT220M25 $1.49
C5 47 nf NTE CML473K100 $0.59 0.047uF 100v
R1 1M5 Had on hand I used a 1M and a 470K in series
R2 3k9 Had on hand Usually $1.00 per five from RS.
R3 10k B Vol Philmore PC745 $1.99 16mm Pot 10K Ohms Linear with switch solder lugs
R4 1K B Gain Philmore PC72 $1.99 16mm Pot 1K Ohms Linear without switch combo term
R5 10 Ohm Had on hand Usually $1.00 per five from RS.
Q1 MPF102 NTE NTE457 $0.99 JFET N-Channel gen purpose amp
U1 LM386 NTE NTE823 $1.89 IC amplifier 1W
Knob Volume control knob Philmore PH3020 $1.29
Knob Gain control knob Philmore PH3020 $1.29
IC Socket Socket for IC (used part for FET) SQ-08-P2 $1.19 Quantity 2 – used one for IC and half of other for FET
Total $15.12
PC board Gen Purp PC Board Radio Shack 276-150 $1.99 Used about half the board
1/4” Jacks Mono Phone Jacks (2) Radio Shack 274-0255 $3.99 One jack for the amp; one for the guitar
Piezo Transducer Radio Shack 273-073 $1.99 This is the transducer/pickup for the guitar
9 Volt Battery Clips Radio Shack 270-324 $2.69 Package of five
Total $10.66
Additional Notes
I scrounged a speaker and a case for this, so those are not included in the total. Wire, solder, etc. is also not included.

Anyway, I hope this is useful to someone. The amplifier is a great design – the only issue I’ve found so far is that it picks up huge amounts of FM radio signal in the upstairs part of my house. In the basement, it works great. The basement is probably a better place for me to make noise anyway. 🙂


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s