Below is the bill of materials compiled with the Advanced Schematic;
somehow it doesn't appear sorted in any reasonable order; unfortunately,
I don't have time to manually rearrange all the entries. The parts listed
below are oriented on breadboard assembly; if you feel comfortable with
surface-mount technology, check with Digikey
for parts in SMD package.
There is also a higher-resolution screen capture
of the circuit diagram.
| Part Type | Designator | Footprint | DigiKey part # | Price, US$ | Description |
| 0.047mF | C2 | P4251-ND | 1.23 | suppresses multiple counts from voltage overshoots | |
| 0.047mF | C3 | P4251-ND | 1.23 | storage capacitor - increasing its value decreases the RPM range | |
| 1.0mF | C4 | P2105-ND | 0.28 | smoothes
the tach readout. Increasing
its value decreases ripple |
|
| 1.0mF 50V | C1 | P2073-ND | 0.51 | isolates the tach input from +12V DC on the coil | |
| 100k | R3 | 0.125W | CT9P104-ND | 1.65 | Tunable: cap C3 discharges through it. Increasing its value decreases RPM range |
| 150k | R1 | 0.5W | 150KH-ND | 0.27(5) | reduces the input voltage on pin 1 of LM2907 chip. Better to mount it in-line |
| 1N4001 | D22 | 1N4001MSCT
-ND |
0.43 | protects
LM2907 input from overvoltage
(clamps it to +6V rail) |
|
| 1N4001 | D21 | 1N4001MSCT
-ND |
0.43 | protects
LM2907 input from overvoltage
(clamps it to ground) |
|
| 1N4001 | D23 | 1N4001MSCT
-ND |
0.43 | protects entire circuit from reverse-polarity connection | |
| 2.2k | R6 | 0.125W | 2.2KEBK-ND | 0.28(5) | determines
the current through LEDs:
I_led = 10 * 1.2V / R6 |
| 2.2k | R5 | 0.125W | 2.2KEBK-ND | 0.28(5) | determines
the current through LEDs:
I_led = 10 * 1.2V / R5 |
| 33k | R2 | 0.125W | 33KEBK-ND | 0.28(5) | provides DC coupling of LM2907 input to the ground |
| 33k | R4 | 0.125W | 33KEBK-ND | 0.28(5) | loading resistor for open emitter output of LM2907 (pin 4) |
| 7806 | U4 | TO220 | NJM7806FA
-ND |
0.65 | 6V DC voltage regulator; any chip from 7805, 7806, or 7808 family can be used. |
| LED | D18 | 67-1045-ND | 0.26 | Amber LED - getting high in RPM | |
| LED | D17 | 67-1045-ND | 0.26 | Amber LED - getting high in RPM | |
| LED | D20 | 67-1047-ND | 1.32(10) | Red LED - redline 1 - OOPS | |
| LED | D19 | 67-1047-ND | 1.32(10) | Red LED - redline 2 - OOPS | |
| LED | D6 | 67-1046-ND | 1.23(10) | Green LED | |
| LED | D5 | 67-1046-ND | 1.23(10) | Green LED | |
| LED | D8 | 67-1050-ND | 1.41(10) | Yellow LED - 2k RPM | |
| LED | D7 | 67-1046-ND | 1.23(10) | Green LED | |
| LED | D2 | 67-1045-ND | 0.26 | Amber LED - getting low in RPM | |
| LED | D1 | 67-1047-ND | 1.32(10) | Red LED - about to stall | |
| LED | D4 | 67-1050-ND | 1.41(10) | Yellow LED - 1k RPM | |
| LED | D3 | 67-1050-ND | 1.41(10) | Yellow LED | |
| LED | D14 | 67-1046-ND | 1.23(10) | Green LED | |
| LED | D13 | 67-1046-ND | 1.23(10) | Green LED | |
| LED | D16 | 67-1050-ND | 1.41(10) | Yellow LED - 4k RPM | |
| LED | D15 | 67-1050-ND | 1.41(10) | Yellow LED | |
| LED | D12 | 67-1050-ND | 1.41(10) | Yellow LED - 3k RPM | |
| LED | D9 | 67-1046-ND | 1.23(10) | Green LED | |
| LED | D10 | 67-1046-ND | 1.23(10) | Green LED | |
| LED | D11 | 67-1046-ND | 1.23(10) | Green LED | |
| LM2907-8N | U1 | DIP8 | LM2907N-8-ND | 2.28 | Frequency - to - Voltage converter chip |
| LM3914N | U2 | DIP16 | LM3914N-ND | 3.29 | LED bar / dot driver chip |
| LM3914N | U3 | DIP16 | LM3914N-ND | 3.29 | LED bar / dot driver chip |
| Breadboard | ~5.00 | Check your local Radio Shack | |||
| Total cost | 26.27 |
Last Updated on 12/24/2012
By Peter Matusov
Email me with any questions or comments - although I very rarely check this mailbox