This last week I have been doing random measurements with both the EC and the JR counter. The ratio between the devices should be 23.636363.. and I have found that to be the case. I have been extremely careful when doing this experiment.
However, if you aren't careful the electronic counter will add revolutions with a slight movement of the wheel. If one extra revolution is added, then your course could be short by about 7'. How many times does a measurer stop? If this happens then errors could occur.
Certifiers have no way in knowing how careful a measurer has been in doing their work. This type of error can't happen with the JR Counter.This message has been edited. Last edited by: Gene Newman,
In the time I have been measuring w/ a Protegé, I have had the wheel stop within 0.05 of the Zero mark maybe half a dozen times, if that. It seems pretty easy to avoid potential problems, and yet I agree w/ Gene there is no way to be sure a measurer has taken those steps.
As a careful measurer using Protege 9, I found a certain peace of mind in mounting two ECs on the wheel, each with a separate magnet. I would know immediately if an extra pulse was received. I also have the wheel marked with a thin strip of duct tape at the zero mark, and another of a different color at the 180 degree point. As I approach a stop, I am careful to stop as close to the 180 degree point as possible, to avoid the chance of a stray pulse. The small extra cost of the second EC is easily overcome by the reduced anxiety!
One other point. Some have suggested that a JR counter might be used along side of electronic counters for verification purposes, but with a Protege counter, that might pose a problem. The Protege counters require an extra revolution each time they are zeroed, to prime the counter, so to speak. (The real reason is a bit more obscure.) Depending on how often the EC is zeroed, and an extra rotation added, the two methods might not seem to agree.
By the way, I dont think cost is the central issue in selecting a counter. The real cost is the opportunity cost, and that is going to be the same regardless.