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Gadget Freak Case #105: KeyCom Helps Keep Everybody in the Same Key
By Design News Staff -- Design News, July 16, 2007
There was dissonance in the church when the pianist and other musicians had to hunt for the key their Music Leader was playing in. Dick's gadget took the guesswork out of the guitar, the meandering out of the mandolin and the pondering out of the piano. The Music Leader communicates the key to the others by setting the display on his Sending Unit via pushbutton or the foot switch, and the Remote Units replicate that display for everyone else. Now, they're all in one A chord (or F, or C, or...).
Build Instructions | View Parts List | Post a Comment
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| Amt | Part Description | Allied Part # |
| 1 | 7-Segment Display, Common Anode, Right Decimal, 0.8 inch | 782-0570 |
| 1 | 7-Segment Display, Common Anode, Right Decimal, 13 mm | 431-0048 |
| 16 | 1N914 Diode | 431-0618 |
| 13 | 2N7000 N-channel MOSFET | 568-0741 |
| 4 | 2N2222 NPN transistor | 248-1004 |
| 4 | 1N4004 rectifier | 266-0004 |
| 1 | 1N4742A Zener, 12V 1W | 431-0332 |
| 1 | CD4001 CMOS Quad 2-NOR | 735-0960 |
| 1 | CD4002 CMOS Dual 4-NOR | 735-1065 |
| 1 | CD4013 CMOS Dual D-flop | 735-1325 |
| 1 | CD4051 CMOS 8-ch MUX/DEMUX | 735-0989 |
| 1 | CD4070 CMOS Quad XOR | 735-1002 |
| 1 | CD4073 CMOS Triple 3-AND | 735-1343 |
| 1 | CD4081 CMOS Quad 2-NAND | 735-1015 |
| 1 | CD4093 CMOS Quad 2-NAND, Schmitt Trigger | 735-1023 |
| 2 | CD4099 CMOS 1 of 8 Decoder/Latch | 735-2444 |
| 1 | CD4516 CMOS 4b Up/Down Counter | 735-1038 |
| 1 | MC14526 CMOS 4b Presettable Down Counter | 568-0877 |
| 2 | RJ25 Right Angle jack w/ panel stops | 374-5770 |
| 1 | 3.5 mm stereo phone jack (needs nut & washer) | 283-0352 |
| 1 | 3.5 mm stereo phone plug w/ strain relief | 283-3291 |
| 2 | Push-button switch, NO, bushing mount w/ nut & washer | 250-3241 |
| Red Tail light tape (Automotive store item) Additional hardware & passive components, See Text | ||
| Get Build Instructions | ||
Talkback
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I would be interested to talk with someone who actually built one of these. I did, but I can't...
- 2007-7-11 11:26:23 EST -
I built one of these a long time ago (about 1972) as part of a physics PhD project. The...
- 2007-8-10 07:58:59 EDT -
the suspended object is non uniform.its kinda doing a pendulum...
- 2007-25-9 01:10:15 EDT -
Are you sure your schematic is correct? I did a quick spice simulation and the 2N3055 never...
- 2007-16-9 06:55:08 EDT -
Gadget freak #107 : none of the links are correct or work...
- 2007-4-9 10:07:25 EDT
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