# The Spark Gap - Episode 14

- Show: [The Spark Gap](https://hardwarepodcasts.com/podcast/the-spark-gap)
- Published: 2014-09-17
- Length: 38m
- Page: https://hardwarepodcasts.com/podcast/the-spark-gap/2014-09-17-the-spark-gap-episode-14
- Listen: https://thesparkgap.net/the-spark-gap-episode-14

## Summary

Hosts Carl and Corey explain the design and operation of an adjustable constant current electronic load (E-load), detailing how to build one using a MOSFET, a sense resistor, and an op-amp. They discuss critical component selection, emphasizing the importance of low temperature coefficient resistors and the Safe Operating Area (SOA) graphs for MOSFETs to prevent thermal failure. The conversation covers practical challenges such as driving high-capacitance gates, managing heat dissipation across different voltage rails, and using parallel resistors to improve precision and power handling.

## Chapters

- [0:00](https://hardwarepodcasts.com/podcast/the-spark-gap/2014-09-17-the-spark-gap-episode-14#t=0) Introduction: Electronic Loads and Use Cases
- [4:09](https://hardwarepodcasts.com/podcast/the-spark-gap/2014-09-17-the-spark-gap-episode-14#t=249) Resistor Selection: Tolerance vs. Temperature Coefficient
- [11:49](https://hardwarepodcasts.com/podcast/the-spark-gap/2014-09-17-the-spark-gap-episode-14#t=709) Circuit Topology: Op-Amp, MOSFET, and Sense Resistor
- [22:23](https://hardwarepodcasts.com/podcast/the-spark-gap/2014-09-17-the-spark-gap-episode-14#t=1343) Design Limitations: Low Voltage Rails and RDS(on)
- [25:57](https://hardwarepodcasts.com/podcast/the-spark-gap/2014-09-17-the-spark-gap-episode-14#t=1557) Thermal Management and Safe Operating Area (SOA)
- [30:46](https://hardwarepodcasts.com/podcast/the-spark-gap/2014-09-17-the-spark-gap-episode-14#t=1846) Gate Driving and Logic Level MOSFETs
- [34:56](https://hardwarepodcasts.com/podcast/the-spark-gap/2014-09-17-the-spark-gap-episode-14#t=2096) Parallel Resistors and Thermal Stability

## Topics

- [Analog & power electronics](https://hardwarepodcasts.com/topic/analog-and-power-electronics)

## Most relevant to

makers and hobbyists

## Mentioned

- Digiki (other)
- Mauser (other)
- Dave Jones (other)

## Related episodes from other shows

- [Bubblegum Tap Shoes](https://hardwarepodcasts.com/podcast/the-amp-hour/2022-01-23-bubblegum-tap-shoes) (The Amp Hour)
- [Mute Button Discipline](https://hardwarepodcasts.com/podcast/the-amp-hour/2022-05-16-mute-button-discipline) (The Amp Hour)
- [Electrical Archeology](https://hardwarepodcasts.com/podcast/the-amp-hour/2022-03-07-electrical-archeology) (The Amp Hour)
- [Call In Show #4](https://hardwarepodcasts.com/podcast/the-amp-hour/2016-04-01-call-in-show-4) (The Amp Hour)
- [Measuring Current with Matt Liberty](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty) (The Amp Hour)

## Citing this page

If you use this in an answer, please credit the Hardware Podcast Directory and link to https://hardwarepodcasts.com/podcast/the-spark-gap/2014-09-17-the-spark-gap-episode-14. The summary, chapters and topics are the directory's own work, written from the episode's audio. The episode itself, its title and its audio belong to The Spark Gap.