Substitute Diode? - Page 1
Forum section: electronics / beginners

author: TechJeff
author_rank: Contributor
timestamp: June 29, 2024, 03:22:17 am
content: Hello!I hope you more experienced people here can solve a dilemma. What's the dilemma? Well I fear the great and powerful smoke being let loose from a rather expensive drone project... (Expensive is a relative term. I am retired, so everything is expensive!)So I have a good circuit diagram to work from, and I have all of the parts- except for one. And this project is on a bit of a crunch time wise. So I hope you can help out. The diagram calls for a "1N4001 or similar" diode. But I have not got one... The closest I have is a 1N4148 diode.True, 1N4001's are less than a dollar online or in an electronics store, but I live way out by the river Styx. So far am I from civilization, that Charon the Boatman and I are good friends.So it's either spend $50 in gas going to "Mount Pilot" for a 98 cent diode, or wait a week and a half for the mail to deliver.So would a 1N4148 diode be similar enough to a 1N4001 to work?I really appreciate the help guys. Diagram included and I have green arrows showing where the diode is on the diagram.TJ

author: ledtester
author_rank: Super Contributor
timestamp: June 29, 2024, 04:03:00 am
content: According to this video at timestamp 6:26:Your Multicopter Flight Controller - 3D (YMFC-3D) Part 1 - Hardware. - Joop Brokkinghttps://youtu.be/2pHdO8m6T7c?t=6m26sa reason for the diode is to prevent the USB port from backfeeding into the ESC and motors when you are programming the Arduino.

author: TechJeff
author_rank: Contributor
timestamp: June 29, 2024, 04:05:38 am
content: I see. But will the 1N4148 work in place of the 1N4001 to stop the backfeed?

author: ledtester
author_rank: Super Contributor
timestamp: June 29, 2024, 04:12:59 am
content: Yes it will. The question is whether it can handle the current from the battery when it's flying.A 1N4148 can only handle a couple hundred milliamps whereas a 1N4001 can handle amps.1N4148 datasheet:https://www.vishay.com/docs/81857/1n4148.pdfThen again, you only need the diode when you are programming it.

author: Kim Christensen
author_rank: Super Contributor
timestamp: June 29, 2024, 04:13:57 am
content: A 1n4148 is rated for around 0.2A or less. A 1N4001, 1N4002.....1N4007 is rated for 1.0ASo if your Arduino + attached circuit draw more than 0.2A, then you'll need the 1n400x diode. (In reality you don't want to pass 0.2A through the 1n4148 since you want a bit of a safety margin)

author: ledtester
author_rank: Super Contributor
timestamp: June 29, 2024, 04:16:29 am
content: Looking at the schematic again, it seems that only the UNO, MPU-6050 and receiver seemed to be powered by current that goes through the diode, so a 1N4148 might work.

author: TechJeff
author_rank: Contributor
timestamp: June 29, 2024, 04:24:57 am
content: Well that was my thought. As I understand this drawing, so long as I do not have the drone battery hooked up at the time of programming, I should not even need a diode.Just need to remember to unplug the battery from the system.Is that correct? This is only for an experiment though, so there should never be a situation where I would have the drone battery on while programming the Arduino.TJ

author: ledtester
author_rank: Super Contributor
timestamp: June 29, 2024, 04:29:51 am
content: The video also mentions backfeeding into the ESC controllers.

author: TechJeff
author_rank: Contributor
timestamp: June 29, 2024, 02:15:25 pm
content: Well I do have some 10A01-T 10A Rectifier Diodes in this kit I bought. Would those work? I mean they might be overkill, but no voltage will get past them, lol.I greatly appreciate your help. My experience is limited to my industrial background. I know what all the components are and I can read electrical schematics well enough, on the small scale at least. But understanding the nuances of components can be tricky for me.TJ

author: ledtester
author_rank: Super Contributor
timestamp: June 29, 2024, 03:45:17 pm
content: Quote from: TechJeff on June 29, 2024, 02:15:25 pmThat should work - here's the datasheet:https://www.mouser.com/datasheet/2/115/ds28010-73787.pdf

author: TechJeff
author_rank: Contributor
timestamp: June 30, 2024, 05:42:28 am
content: Ok, went over things again. The diode is there so if you want to reprogram the Arduino while it is still connected to everything, the USB voltage into the Arduino won't try to spin the motors.How are you finding these datasheets? When I type in my diode, all I get is companies trying to sell me diodes for page after page.TJ

author: Kim Christensen
author_rank: Super Contributor
timestamp: June 30, 2024, 03:15:16 pm
content: Mouser, Digikey, Newark, etc, while wanting to sell you components, usually have the datasheets. Use their search with your part number.Their parametric search is also pretty good when you're looking for a part for a project you're designing. I use Digikey's search.

author: shapirus
author_rank: Super Contributor
timestamp: June 30, 2024, 03:36:36 pm
content: Quote from: TechJeff on June 30, 2024, 05:42:28 amTry addingfiletype:pdfto your search query (assuming you use google search, not sure if this parameter is called the same with other engines).

author: TechJeff
author_rank: Contributor
timestamp: July 01, 2024, 03:34:01 pm
content: Thanks everyone- greatly appreciated.TJ

author: MathWizard
author_rank: Super Contributor
timestamp: July 02, 2024, 12:58:28 pm
content: Yeah those ones you have can handle a lot of current.I have a small collection of PCB's and part's (besides stuff I buy), mainly from LCD/LED TV's, and printer's. Things like 1N4001's are still pretty common, in both through-hole and SMD. It breaks my heart to think of the electronics that I owed, that got thrown out over the years.If you drive anywhere and see some electronics waiting to go to the dump, take them for sure. I have lots of cool thing's to try, like all the motor's and sensors on printer's.

author: Ian.M
author_rank: Super Contributor
timestamp: July 02, 2024, 01:26:40 pm
content: The Arduino Uno DC in 5.5/2.1 mm barrel jack has a suitably rated diode between its center pin and Vin on the Power header, so you *could* simply omit that 1N4001 and connect the center pin of the barrel jack to Battery + to use the on-board diode. Keep the other Vin pin connections - they are used to sense battery voltage.Alternatively, as Mathwizard points out, you can probably find a suitable diode from any scrap boards you have. Nearly anyDO-41package diode is likely to have suitable current and voltage ratings. Simply check the salvaged diode is *NOT* a Zener by googling its markings and that it's Vf is in the 0.5V-0.7V range indicating a silicon PN junction type.

author: TechJeff
author_rank: Contributor
timestamp: July 02, 2024, 06:33:17 pm
content: Thank you Ian and Wizard for your help. I already placed a 10 amp Diode on the drone, from from a previous project. It's total overkill, but it works- ain't no voltage going through there, lol. I will try it without a diode in my next rendition.Great idea about raiding waste electronics! I will be picking over anything I throw away from now on!At his point, I plugged it in and the code ran- it works! I just hope the last bit of kit arrives soon! I need an antenna module for my radio and that's it!I still need to hookup the antenna module for the drone today and if the parts arrive, we might be flying!Thank you all very much!TJ