Electronics > Beginners
help with potential voltage spikes
psubond:
I saw Great Scott's boost converter write-up and video. He mentioned that there was a problem with voltage spikes from the inductor when power was turned off, link found here https://www.instructables.com/id/DIY-Boost-Converter-How-to-Step-Up-DC-Voltage-Effi/
My question is, would a flyback diode across the inductor like one used for a motor or relay work with his schematic for eliminating the spike when power is turned off?
Mario87:
From what I understand...yes it should work. However there are more knowledgeable people than me on here who may well be able to explain as to why it would not work. I myself cannot see a reason.
After all, a relay is just an inductor (coil of wire that magnetizes when voltage is applied), and they use flyback diodes, but as above, there may be something I am missing that someone else can clarify better.
Zero999:
Yes it will work, but I wouldn't expect it to be very efficient, as the inductor appears to be the sort used for EMI filtering, rather than switched mode power supplies.
Also make sure you use the IRLZ44N, rather than the IRFZ44N. A logic level MOSFET is essential for decent performance with 5V of gate drive.
oPossum:
Towards the end of the video he mentions that the output voltage will rise when the load is disconnected. This is due to the microcontroller firmware not implementing a proper control loop. The easy hardware fix is to use one of the may switching regulator chips rather than a microcontroller.
Don't put a diode in parallel with L1. It will no longer work if you do that.
Mario87:
--- Quote from: oPossum on October 04, 2018, 01:45:55 pm ---Don't put a diode in parallel with L1. It will no longer work if you do that.
--- End quote ---
Can you explain why it would stop working?
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