There are many types of digital pedometers on the market. They all operate by sensing a slight AC vertical acceleration superimposed onto 1 g DC. Usually a coiled spring moves a small magnet that hovers over a hall effect xdcr. For a 5 g application, this concept could probably be...
Thanks, all. One issue with the circuit is its symmetry. A simple circuit analysis is useless in that, with ideal components, the base current splits evenly (like balancing a ball on the end of your finger). In reality of course the parameters aren't exactly the same and the base current...
Thanks Skogsgurra. Transistor hFE definitely is a factor. Vbe increases at cold, making the situation even worse by reducing the base current.
I've also added a series RC network across the B-C of each transistor as an LPF (adding to the Miller capacitance). This helps with starting up, but...
We have a relatively old (ca. 1970s) design for a DC-DC converter which centers on a saturable core toroid transformer. A center tap feedback winding provides the signals to the bases of two complementary NPN transistors; these transistors nominally switch at around 5 kHz.
At room temp and...
