Using the following:
- R1 4.7-10K
- R2 4.7-10K
- R3 10-20K
- C1 1000uF 16V
You will get:
Time On = .693*(R1+R2)*C1 = 6 to 14 seconds
Time Off = .693*R2*C1 = 3 to 6 seconds
Frequency = 1/(0.693*(R1+2*R2)*C1)
This doesnt seem like it will be even close to the OEM spec. Using the other circuit mentioned, you get:
R1 = 100 Ohms
R2 = 3*10^6 Ohms = 3M Ohms
C1 = .22 mF = 220 * 10^-6 F = 220 uF
Then:
Time On = .693*(R1+R2)*C1 = 457 seconds
Time Off = .693*R2*C1 = 457 seconds
Frequency = 1/(0.693*(R1+2*R2)*C1) = .0011 Hz
Which also is totally off. So for those of you who built these circuits and got it to work properly, I'm very surprised. In fact, I'd like to hear back from someone who actually used the specs provided in this post and was successful.
To answer the question regarding figuring out the ohms of resistors, use the following color chart:
http://www.csgnetwork.com/resistcolcalc.html