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Ideas for Design Vol. 3, No. 1 (Download)

Oct. 19, 2021
This issue presents a 555 timer-based circuit to drive a power MOSFET, a capacitive touch switch built using a PLL plus capacitor and triac, and a circuit that handles high-current NiCd charging apps.

This article is part of the Ideas for Design Series: Volume 3

Volume 3 kicks off with these three popular classic Ideas for Design:

  • The venerable 555-type timer makes an effective driver for power MOSFETs, but you have to understand the drive situation when selecting the correct variation of the basic timer. This idea shows how the wrong choice led to unreliable operation and failure, and the basic analysis that points to the correct choice.
  • A PLL-based circuit implements a touch-switch circuit using the PCB or small metal pads as sensors. It is radiometric and thus insensitive to changes in temperature and supply voltage.
  • A simple circuit supports charging of NiCd cells at high rates while avoiding common problems caused by overheating or overcharging, which can degrade performance and even damage the cells. The design uses low-cost thermistors and a non-critical, basic op amp.

These links are to the articles, while the Download button provides access to the PDF ebook that collects together all of these articles:


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