Best genral purpose power mosfet. - Page 1
Forum section: electronics / beginners

author: David97
author_rank: Contributor
timestamp: July 18, 2014, 01:36:10 am
content: Hi everyone (1st post). I'm looking for a inexpensive power mosfet for testing and for projects. The purpose is to control medium to large loads such as motors. An example is a project I'm working on now, where I need to switch a cars ignition coil on and off using a 555 timer to make a pulse jet igniter. I have also been experimenting using windsheild wiper motors for robots, and need a suitable fet to do this. I know I haven't given much info, but I just need something in my parts draw for these types of applications.Looking to make a bulk order of both N-channel and the P-channel equivalent.Thanks for any help.

author: TerminalJack505
author_rank: Super Contributor
timestamp: July 18, 2014, 02:57:06 am
content: I'd vote for IRF530 and IRF9530.Edit: Said IRF930 but meant IRF530.

author: kingofkya
author_rank: Regular Contributor
timestamp: July 18, 2014, 04:19:11 am
content: I like to have to have a selection:)I have been useing these guys for common parts lately:http://www.taydaelectronics.com/There is quite a few cheap ones to get you started you may want to do a search on whatever you order to make sure its not a discontinued model though.

author: David Hess
author_rank: Super Contributor
timestamp: July 18, 2014, 05:37:35 am
content: Quote from: David97 on July 18, 2014, 01:36:10 amDriving an ignition coil and switching a motor are different enough that I would want to use different parts or at least different switching circuits. An ignition coil in particular is a good place for a MOSFET to drive a bipolar cascode switch although in that case the MOSFETs could be similar.QuoteMOSFETs do not have complementary pairs to the extent that bipolar transistors do. For a given voltage and die size which determines the wattage and gate charge, the P-channel MOSFET will have a significantly higher drain to source resistance and lower current rating. For equal drain to source resistance, voltage, and current ratings, the N-Channel MOSFET will have a smaller die size yielding lower wattage and lower gate charge.So for linear applications I pick MOSFET complementary pairs by matching their power rating as a proxy for die size. In switching applications where rated power dissipation is usually irrelevant, I pick them based on voltage and current.As far as finding a low cost generic part, I would just search Mouser or Digi-Key or similar for P-Channel devices in TO-220 packages and sort by price and then look for the N-Channel part matched by power for analog and current for switching.

author: David97
author_rank: Contributor
timestamp: July 18, 2014, 10:19:36 pm
content: Thanks everyone.

author: rob77
author_rank: Super Contributor
timestamp: July 18, 2014, 11:31:43 pm
content: i like the hexfets from IR.IRFZ34N N-chan + IRF9Z34N P-chanthe IRFZ34N has a relatively low gate capacitance - approx. 700pF , so it's easier to drive them with "weak" outputs.

author: retrolefty
author_rank: Super Contributor
timestamp: July 18, 2014, 11:48:34 pm
content: "logic level" power mosfets are nice if you need to interface with TTL digital output voltage.