Your explanation of the use the diode is the best of have seen out on the internet. Thank you for posting!!
@OldSloGuy2 жыл бұрын
Almost. What you need is a snubber. A snubber is a diode in series with a resistor. So, why do you need the resistor. In many electronic circuits, devices are protected from inductive kick back by a diode. The coil in a contactor is not puny like 100 turns of #35 wire on a ferrite coil, it is probably as big as the coil in many magnetos. So, in effect, the diode is shorting out a spark plug when it fires. The diode has a junction that will breakdown because of very high currents in the microsecond range. So, the diode case won't show excessive heat before failure. When the diode junction breaks down, it becomes a resistor and current flows in both directions, shorting the power supply and you have a classic smoke test. A resistor in series with the diode is chosen to limit the current through the diode while also limiting the voltage spike in the surrounding circuit.In most cases, reducing a thousand volts to say 50 volts wins the day. Since the resistor has a higher resistance than the conducting diode it is in series with, most of the energy is dissipated as heat in the resistor instead of the diode. Since resistors are designed to get hot, they can withstand energy dumps that the diode's junction cannot. A diode alone always works for coils connected to delicate printed circuit board leads. That is a low power situation, contactors in aircraft are not comparable. One last thought, make sure you use a non-inductive resistor. Wire wound resistors have measurable inductance.
@GrantsPassTVRepair Жыл бұрын
You would think this would be a standard feature on every automotive contactor. Thanks for the suggestion that we add one to our contactor.
@siTTinLo3 жыл бұрын
Thank you. I think this simple diode is the reason my friends lift keeps burning up motor controllers. I will pass this info along.
@Jwood7374 жыл бұрын
Great explanation - just what I was looking for
@mihir777 Жыл бұрын
4:48 Department of sweeping generalizations 😅 Reminds me of ministry of silly walks
@ajscain500 Жыл бұрын
😂😂😂
@moggywan6 жыл бұрын
I was involved in building "specialist" vehicles for over 20 years We used contactors sometimes referred to as Klixons to conect dual charge or auxilliary batteries and as generator starters Beware! do not buy a cheap contactor, our buyer, being a cheapskate started ordering chinese components because of price After numerous failures we cut open a few units, the core inside the coil was a simple bolt! This contacted the heads of the two bolts that the wiring was attached to In a couple of instances the bolt heads fused together causing the starter to engage all the time burning out the starter or destroying the ring gear, if in the battery master situation it might mean not being able to switch off systems Buy the best, you will not be dissapointed, also it could save an engine or a life!
@B61Mod122 ай бұрын
great explanation. so, just need to work out, what size diode to use in what system...?
@tomthompson74004 жыл бұрын
never thought of this , interesting video.
@uptightnonchalant18577 жыл бұрын
It just kills me to see relays mounted in the vertical fashion in aircraft. One hard landing and a bounce and you can engage the starter, sheer a few teeth or worse. Relays should be mounted in the horizontal fashion. Especially in aircraft. Just my 2 cents.
@jeffdeuchar10894 жыл бұрын
Umm, no. If you mount them horizontally, you are asking for a sticking solenoid. So how to over come this? Mount the starter solenoid so that gravity pulls it open (usually looks like upside down) and the opposite for the master. I've pulled apart a couple old relays and there is quite a bit of shavings (or something) in there that best fall to the bottom.
@vhkillah2 жыл бұрын
Love this,should always put a diode across the coil windings to stop back electromotive force
@mmichaeldonavon2 жыл бұрын
So true - there will be no induced voltage spike coming from that large number of windings in those relay coils.
@007floppyboy8 ай бұрын
@@mmichaeldonavon trouble is, a diode slows the operating of the opening contacts, and this leads to burning of them and premature wear. Use a Diode in series with a resistor.
@briandavis99754 жыл бұрын
Thank you for sharing.
@shmele_nsk Жыл бұрын
thank you so much!
@texan2560Ай бұрын
every electric coil device usually needs to be protected from back EMF. Relays, soleniods, etc.
@michaelcuoco32046 ай бұрын
Hi my name is Michael and I've built me a Porsche 914 with a 427 Stroker Motor, and I've burnt 2 key switches, so a friend of mine that owns another Porsche Shop told me to put a starter relay like the Ford type, naturally I wanted the best so I went on Amazon and bought a MySpare relay 4 post they gave me to diodes one bigger and one smaller, I couldn't get it to work then I was reading the reviews, and a old farmer said that ya have to ground one of the small posts,so I've done more homework wich led me to your KZfaq, and I'm aware of better Quality Relay, and I am all about better and nothing burning up ,I run Holley Snider Fuelinjected and Msd Timing and Control, that has to go Straight to the Battery, I'm thinking perfect spot for the Diodes, also what type of Lamar or Skytech should I use Before it goes to the Stater Solinoid on the starter ,and the for post do I ground one of the small posts and still run a Diode across both small Terminals ? Aircraft stuff is the Quality I want to be at Overkill every thing no Fires no frying all my Electronics I have a lot of money in it just like Aircraft, can you help me please
@spikekavalench2 жыл бұрын
Brilliant!
@ajscain500 Жыл бұрын
When you talk about the direction of electric flow do you mean “ Conventional “ current flow ( actually proton flow direction ) or actual electron flow ?
@GrimReaper-ly8zk3 жыл бұрын
Would you also use one on the motor +. -. Wouldn't it also create a inductive load when disengaged maybe causing internal damage.
@BarryBranton4 жыл бұрын
How would you snub the transient from a mechanical latching contactor?
@raho247816 ай бұрын
how do you use a Diode on a 3 post older style Relay "Solenoid"
@challenger2ultralightadventure5 жыл бұрын
Use a 24 or 40 Volt MOV instead of a Diode! (Metal Oxide Varistor) It is not polarity sensitive, and keeps the operating characteristics of the relay (contactor) intact! What that simply means, is if a diode is used, it holds the magnetic field intact for upwards of 250 millisecond, allowing the field to collapse slower, thus reducing the voltage spike! The MOV does not slow the response time of the relay like the diode does. FYI, your common variety surge and lightning suppressor uses two 250 Volt MOV's to protect your electronics at home. Diode use for surge suppression is NOT the recommended way to address this problem of voltage spikes from relays. Use the device designed for that purpose, use a 24 or 40 Volt MOV!
@daleyoung873 жыл бұрын
This is better than a diode? What kind should I get and how to install? Just like diode?
@007floppyboy8 ай бұрын
@@daleyoung87 MOVs are good and they are better than a diode on their own, but if you want the best result, ie fast closing time, fast opening time, and the least amount of induced voltage, use a Diode in series with a resistor. An MOV on its own will still allow spikes of 2-3 times that of the supply voltage, much better than no protection of around 5-10 times a back emf of the supply voltage, sometimes more. For a 12v supply a diode and a series 120-150ohm resistor.
@anjumshuguftha99565 жыл бұрын
thanks for the video:)
@KStewart-th4sk5 жыл бұрын
Is grounding the circuit through the switch shown here a uncommon way of wiring the circuit? Most times I see running power to the switch---to the solenoid and THEN to ground. There is no information given as to the # of the diode (specifications) to use either. For the uninformed, like me, what size of diode should be used on a 12 or 24 volt starter solenoid??
@challenger2ultralightadventure5 жыл бұрын
Don't use a diode! Use a 24 or 40 volt MOV! (Metal Oxide Varistor) It's not polarity sensitive, and is designed specifically to handle voltage spikes. For a 12 volt system you could use a 24 volt MOV, and a 40 volt MOV for a 24 volt system. The voltage spike from a relay that has been de-energized can reach 10's of thousands of volts! To install an MOV, just bridge the two terminals of the relay coil.
@mmichaeldonavon7 жыл бұрын
And, my two cents. I see that your explanation used "Conventional Current Flow" theory - From Positive to Negative. In all reality, the negatively charged particles, the "current" will flow from ground (the air frame, effectively) through the coil, to the Positive terminal of the battery. No big deal, in that the diode is "reversed biased" across the coil, in its installation, then forwarded biased (i.e. the short ckt) when the mag field collapses. Good info though. Thanks. N-6395T
@samualwhittemore2286 жыл бұрын
Michael Donavon Yea but if you explain it that way people will put the diode in backwards - because of it's conventional labeling. my guess is that muy mucho confusion is setting in about now for the electrical neophytes. Ha Ha ;))
@tomclark62715 жыл бұрын
You were in the Navy, weren't you!
@flexairz5 жыл бұрын
Try changing that after more than 100 years of drawing circuits with conventional current flow theory.
@challenger2ultralightadventure5 жыл бұрын
You only confuse people with facts. LOL Although you are 100% correct, electron flow is usually only considered when designing, and even then not all the time. I use electron flow all the time, but then again, I'm a Ham Radio operator, and it's the best way of dealing with RF circuits. Conventional Current Flow is a hold over from a time when we didn't understand what electricity truly was, and it's relationship to the structure of the atom. But because it was in such common use, it was too difficult to suddenly tell everyone to change. It's like the VHF radios in aircraft. If only they went FM! But to change all aircraft world wide would be near impossible, like changing the concept of current flowing from positive to negative, to Negative to positive.
@arcanondrum65432 жыл бұрын
The Diode has a Stripe on the exterior, closer to one lead than to the other. Electrons will flow through from the side furthest from the strioe. They will NOT flow in the opposite direction. I hate Comments from people who don't know and won't learn first.
@lllCANDYMAANlll2 жыл бұрын
4:29 Does this dissipate through heat?
@ajscain500 Жыл бұрын
Where to buy a master starter ?
@Hopeless_and_Forlorn2 жыл бұрын
I need to know the duration of a split moment in either nanoseconds or Fermi Times, your choice.
@1shARyn37 жыл бұрын
Operative word when requiring a diode is "Inductor" Diodes should be used when/across motor circuits as well as solenoid circuits
@whodjaNC6 жыл бұрын
Gwen Walcott i
@flexairz5 жыл бұрын
Well it was the subject of the video. Whats your point?
@lnlilglhltllllll18712 жыл бұрын
So ...ac current is a positive that collapses then a negative collapse...and each collapse increases
@waytooslow5 жыл бұрын
so a stupid question here -- is a SSR usable in aircraft?
@leeackerson25794 жыл бұрын
Not a stupid question. There are D.C. solid state relays as well as the familiar A.C. SSRs. The advantage of using mechanical relays though, is they are immune to voltage spikes and short surges of high current, but SSRs may not be so forgiving.
@zmanmd16416 жыл бұрын
The diodes I have seen always have letters and numbers on them. These numbers must indicate the types, sizes or strengths of the diode. So what "size" and type of diode is appropriate for this application?
@samualwhittemore2286 жыл бұрын
ZManMD Use a 1N5408 That will give a 1000 volt repeated reverse voltage spike protection and 3 amps of forward current. The 5400 only provides 50 volts protection, the 1N5404 provides 400, the 5406 provides 600, 5407 is 800, 5408 is 1000.
@johnsdsl6 жыл бұрын
There's nothing wrong with a 1N5408, but the spike is typically in the forward direction for the diode.
@stevebigler5 жыл бұрын
Sam... I use starter solenoids in some 4x4 upgrades to remote solenoid applications with a pb start. So (big lug) #1 goes to starter, big #2 to the batt, and "s" start trigger to the push button. the "i" (ignition??) terminal is always left bare. Where is the diode in this relationship? (And to make matters more confusing... [why are solenoids always unmarked???!!!] on some constant duty installs others have done for me... they run the "i" to ground. I don't get it...) Thanks in advance. GotScout@gmail if easier.
@flexairz5 жыл бұрын
@@samualwhittemore228 Diode do not provide the protection in voltage. What you mean with the voltage its the maximum reverse voltage the diode is built for.
@challenger2ultralightadventure5 жыл бұрын
Do not use a diode!! Use a 24 to 40 volt MOV! (Metal Oxide Varistor) The MOV is specifically designed to deal with spikes in current, the diode is not. The diode works, but it also alters the operating characteristics of the relay, slowing their reaction time down. The MOV does not change how the relay works, it's not polarity sensitive, and is what nearly all off the shelf lightning suppressors for home use are made with.
@rysammy4 жыл бұрын
I do not understand why the diode is connected between the pos, that activates the coil, and the ignition post if the coil as it is a different circuit and would not be effected. Shouldn't the diode be in series with the positive wire that feeds the coil? My application automotive. Oh, I see you are keeping the solenoid powered by the jumper wire.
@dissociativecat74954 жыл бұрын
diode for DC, resistor capacitor for AC
@arcanondrum65432 жыл бұрын
Actually 4:30 the Diode presents an OPEN Circuit to the reverse current. The open switch means that the Diode has NO connection to Ground so it cannot _"[present] a short circuit"_ to Ground nor to any other node. 4 years of it in college then I switched to Software.
@HomebuiltHELP2 жыл бұрын
Look a little closer! While I misspoke about shorting to "ground", it does indeed short the current across the coil itself, not to ground. The effect is the same - the switch does not see the reverse voltage spike. Make sense?
@arcanondrum65432 жыл бұрын
@@HomebuiltHELP No, a Diode simply acts like a switch. In one direction it is always open. In the other direction, it is always closed.
@HomebuiltHELP2 жыл бұрын
@@arcanondrum6543 Yes - we agree on that! While the coil is energized, the diode is reversed bias and looks like an open switch. The reason to have this diode is that when the coil is de-enrgized, the electromagnetism of the coil collapses - a strong REVERSE voltage is induced in the coil - which the diode NOW CONDUCTS - and shorts the current. This phenomenon is the whole point of this video. This diode bleeds off (shorts) the otherwise high reverse voltage that otherwise would spark across the switch.
@petercunningham34692 жыл бұрын
Backfeed
@jorgezuni28182 жыл бұрын
Why because you may encounter a Voltage Drain . So to prevent that we use a Diode
@barrybarry66893 жыл бұрын
Totally incorrect on your explanation. 1 - The diode does NOT go in series with the ground power lead. 2 - - Where did you get 100 times lager from? YES there is a large Reversed Induced Voltage (RIV). 3 - It is the RIV that you want to ground out. But the diode has to be connected in reverse bias so the collapsing field is in forward bias and grounds out.