In Motorcycle Safeguard with Touch Censor, many people have complained that it is too sensitive. How it work and how to reduce its sensitivity?
Actually, the resistor from the base of Q2 to the collector of Q1 serves to do locking so that when the circuit was already ON, then it will be preserved remains ON. The smaller the value, the more powerful this resistor do locking. In addition, the value of the resistor also affects it’s sensitivity. The larger the value, the more sensitive to the signals received at the sensor. On that design, we wanted a strong locking (using resistors with low value) but also wanted to keep sensitive (using resistors with high value). A combination of mutually opposite-back. Therefore, we split the work of resistor using D2 become a high R2 (1M) to keep it sensitive and low R1 (100K) for strong locking. After a lot of experimenting the circuit, it is known that the circuit thus far too sensitive. Then I did the experiment again, and found that 100K resistor already quite sensitive. Well, when the resistor for locking or sensitivity regulator using the same value, that is 100K, then the separation work of resistor is not needed anymore, it means the diode D2 is also not needed anymore. So, we can dispose of the D2 and the R4 and use only R2 only. I’ve discussed this kind of conversion in the comments, but most of us are too lazy to read the comments. When I still open the comments on that page, the question of sensitivity is still always asked even if the answer is already there. And when the comment is closed, then the question moves to facebook on electronics groups. Therefore, I think if I give a circuit that the sensitivity is already reduced using the ways that are already discussed in the comments, then there is no longer question “Why this highly sensitive?”. The circuit that the sensitivity had already been reduced is as follows:
The circuit like this is what I use on KeyMot SS.