![]() With the load current effectively zero, \$R_2\$ and \$R_4\$ act as an uncontrolled (but small) collector bypass current that pulls up on \$Q_1\$'s collector enough to likely yield an almost zero \$^\$ and it is now that we need to focus much more closely on precisely when the foldback might happen.īut even after the change-over, when the current direction in \$R_2\$ has reversed, \$Q_1\$ is still heavily saturated (in a properly designed circuit.) \$Q_2\$'s collector hasn't yet replaced enough of it to push \$Q_1\$ out of saturation. \$Q_1\$'s base-emitter junction is mostly just a diode junction here. \$Q_1\$ is fully saturated and the current in \$R_1\$ is almost the same as the current in \$R_3\$. ![]() Simulate this circuit – Schematic created using CircuitLab Foldbackklammer 3D CAD Model Library GrabCAD Join 9,160,000 engineers with over 4,760,000 free CAD files Join the Community The CAD files and renderings posted to this website are created, uploaded and managed by third-party community members. The handles allow easy release of documents. I've used a small green arrow to point out this detail: if you carefully look, you can see that the direction through \$R_2\$ is diametrically opposite in these two cases. Bring a little fun to organize your documents with different color foldback clips. Diagram 2 shows the arrangement where the load current is moving sufficiently towards foldback that \$R_2\$ is now supplementing \$Q_2\$'s base current (along with current through \$R_4\$) and foldback is near. Diagram 1 shows the arrangement where the load current hasn't yet risen to the point where \$Q_2\$'s collector current is significant and where the current in \$R_2\$ is pulling up on \$Q_2\$'s base, keeping it out of a foldback behavior. ![]() These diagrams are arranged so that you can focus on their operation during two different phases. Mengen Aktenklammern Clip Vielzweck Klammern. I've drawn two versions of the same schematic below. Foldback klammern Heftklammer Binder Clips Dokumenten Clip Papier schwarz.
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