Mystery component, what is DI1? Looks like a diode, but no bands

I am troubleshooting a cooktop spark module. There is a component that looks like a small glass cased diode, but it isn't a diode. There is no band indicating cathode and when removed from the circuit, it measures open both directions. There are no markings on it whatsoever.

There are other diodes on the circuit board, but they are labeled as D1, D2, etc whereas this component is labeled DI1. In the circuit, it is series with a 22 ohm resistor before going to the gate of an SCR.

It is not burned out because the circuit works fine for a while, before the transistor than fires the SCR fails.

Thanks for any ideas! Tom

by lapsmith
November 03, 2020

Could it be a Reed Switch?

by vanderghast
November 04, 2020

Oh, good guess. But don't think so as there are no metallic, magnetic, or moving parts nearby. Thanks!

by lapsmith
November 04, 2020

the answer is found here This component is called a DIAC

by cbryhy
November 07, 2020

1 Answer

Answer by cbryhy

This is called a DIAC. Thats why the identifier is DI. It is used to trigger TRIAC. It is a bidirectional device and the multimeter will act as an open circuit while connecting across a diac. change the multimeter polarity across the diac whether it is showing open circuit in both cases. If the multimeter is showing any reading in any direction it is faulty and needs replacement.

+2 votes
by cbryhy
November 07, 2020

Your Answer

You must log in or create an account (free!) to answer a question.

Log in Create an account

Go Ad-Free. Activate your CircuitLab membership. No more ads. Save unlimited circuits. Run unlimited simulations.

Search Questions & Answers

Ask a Question

Anyone can ask a question.

Did you already search (see above) to see if a similar question has already been answered? If you can't find the answer, you may ask a question.

About This Site

CircuitLab's Q&A site is a FREE questions and answers forum for electronics and electrical engineering students, hobbyists, and professionals.

We encourage you to use our built-in schematic & simulation software to add more detail to your questions and answers.

Acceptable Questions:

  • Concept or theory questions
  • Practical engineering questions
  • “Homework” questions
  • Software/hardware intersection
  • Best practices
  • Design choices & component selection
  • Troubleshooting

Unacceptable Questions:

  • Non-English language content
  • Non-question discussion
  • Non-electronics questions
  • Vendor-specific topics
  • Pure software questions
  • CircuitLab software support

Please respect that there are both seasoned experts and total newbies here: please be nice, be constructive, and be specific!

About CircuitLab

CircuitLab is an in-browser schematic capture and circuit simulation software tool to help you rapidly design and analyze analog and digital electronics systems.