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Appendix 1: Build options
Pulse level:
R14, R15 and/or trimmer R16 set the clock output pulse voltage level. The following options
are suggested:
•STANDARD BUILD: 10V pulse: R14 = 1.2K, R15 = 11k, R16 OMITTED
•5V pulse: R14 = 1.8K, R15 = 1.5k, R16 OMITTED
•VARIABLE PULSE LEVEL: R14 = 1.5k, R15 OMITTED, R16 = 50k Trimmer
Remember to add the trimmer to your parts order if you are installing this option.
If you are using R16, install it and then R15 SHOULD NOT BE INSTALLED. Make sure the multi
turn trimmer is oriented so that the screw is above the circle on the silk screen.
Range:
C3-C6 set the HI range of the clock and C7-C11 set the LO range of the clock. Each range is
determined by a bank of parallel capacitors equivalent to C(HI) and C(LO).
The clock values can be determined by entering different values for C in the range calculation
spreadsheet inclued in the documentation link.
Simply enter capacitor values in column A to find clock frequencies in columns D-E
For more extensive customization you can change the values of R1 and VR1.
The spreadsheet uses the following formula:
F = 1/2.2*(R4 +VR1)*C in Megohms and microFarads. F (freqency ) is the inverse of the clock
period.
You can use one ar more of the capacitors in each bank to obtain the equivalent values required
With the capacitor values suggested in the BOM, the approximate clock frequencies are:
