epsilon12 parts: Mouser: 1 3/8" multi-turn cermet trimpot 1K (Vishay-Sfernice) 72-T93YA-1K $1.20 (Bourns) 652-3296W-1-102 $2.20 (Alternate) 2 1/8W 1% metal film resistor 3.32K (Vishay-Dale) 71-RN55D-F-3.32K $ 0.32 6 1/8W 1% metal film resistor 10K (Vishay-Dale) 71-RN55D-F-10K $ 0.96 1 1/8W 1% metal film resistor 100K (Vishay-Dale) 71-RN55D-F-100K $ 0.16 1 1/8W 1% metal film resistor 1K (Vishay-Dale) 71-RN55D-F-1.0K $ 0.16 1 1/8W 1% metal film resistor 475K (Vishay-Dale) 71-RN55D-F-475K $ 0.16 3 tantalum capacitor 22uF/25V (Kemet) 80-T350H226K025 $ 5.94 !!! 1 ceramic capacitor 0.1uF/100V (Kemet) 80-C320C104J5R $ 0.24 1 film capacitor 1uF/63V (AVX) (AMB audio shop) $ 0.40 (Wima) 505-MKS21.0/63/10 $ 1.05 (Alternate) (Vishay-Roederstein) 75-MKT1818510065 $ 0.72 (Alternate) 2 non-polar capacitor 100uF/16V (Nichicon) 647-UVP1C101MPD $ 0.72 1 OPA551PA operational amplifier (TI) N/A (use Digikey or Newark) 1 TL081CP operational amplifier (TI) 595-TL081CP $ 0.63 5 NPN 2N3904 (Vishay) 625-2N3904 $ 0.15 1 PNP 2N3906 (Vishay) 625-2N3906 $ 0.05 1 NPN small signal darlington (Fairchild) 512-MPSA14 $ 0.12 1 12V 500mW zener diode 1N5252B (Fairchild) 512-1N5252B $ 0.11 3 diode 1N4148 (Fairchild) 512-1N4148 $ 0.15 1 12VDC DPDT relay G6A-234P-ST-US-DC12 (Omron) 653-G6A-234P-DC12 $ 4.63 2 DIP-8 socket (Mill-Max) 575-113308 $ 0.70 2 TO-92 clip-on heat sink (Aavid) 532-575200B00 $ 0.54 (for high supply voltages) Subtotal: $ 36.50 --------------------------------------------------------------------------------------------------------------------------- Digikey: 1 3/8" multi-turn cermet trimpot 1K (Murata) 490-2874-ND $0.85 (Bourns) 3296W-102-ND $2.50 (Alternate) 2 1/8W 1% metal film resistor 3.32K (Yageo) 3.32KXBK-ND $0.54 (5) 6 1/8W 1% metal film resistor 10K (Yageo) 10.0KXBK-ND $1.08 (10) 1 1/8W 1% metal film resistor 100K (Yageo) 100KXBK-ND $0.54 (5) 1 1/8W 1% metal film resistor 1K (Yageo) 1.00KXBK-ND $0.54 (5) 1 1/8W 1% metal film resistor 475K (Yageo) 475KXBK-ND $0.54 (5) 3 tantalum capacitor 22uF/25V (AVX) 478-1877-ND $7.35 !!!!! 1 ceramic capacitor 0.1uF/50V (Kemet) 399-2054-ND $0.21 (kemet) 399-2081-ND $0.21 (Alternate) 1 film capacitor 1uF/63V (AVX) (AMB audio shop) $0.40 (Vishay-BC) BC1622-ND $4.06 (10) (Alternate) 2 non-polar capacitor 100uF/16V (Panasonic) P1167-ND $0.86 1 OPA551PA operational amplifier (TI) OPA551PA-ND $3.94 1 TL081CP operational amplifier (TI) 296-7203-5-ND $0.48 3 NPN 2N3904 (Fairchild) 2N3904FS-ND $0.48 1 PNP 2N3906 (Fairchild) 2N3906FS-ND $0.18 1 NPN darlington MPSA14 (Fairchild) MPSA14-ND $0.28 1 24V 500mW zener diode 1N5252B (Microsemi) 1N5252BDO35MSCt $0.21 (Diodes Inc) 1N5252BDICT-ND $0.36 (Alternate) 3 diode 1N4148 (Fairchild) 1N4148FS-ND $0.21 1 12VDC DPDT relay G6A-234P-ST-US-DC12 (Omron) Z106-ND $4.68 (See parts list) 2 DIP-8 socket (Assmann) AE7313-ND $1.86 2 TO-92 clip-on heat sink (Aavid) HS251-ND $0.84 (for high supply voltages) Subtotal $43.85