12DC Sockets

[KeepItSimpleStupid]

Breakdown when it say refers to a capacitor is destructive. Capacitors are rated in WV or Working Voltage. When the breakdown is exceeded, a hole gets punched in the dielectric which is unrecoverable.

In the other case, as long as the current is limited, there will be do damage.

TVS
A TVS is designed to control spikes, but it does have a particular time response. Gas discharge tubes are another way to deal with MAJOR surges.

Rectifiers
Diodes and rectifiers are the same UNLESS you happen to be in the plating industry. For some dumb reason: https://www.caswellplating.com/kits/rect.htm

You will learn the hard way when you span multiple industries the terms are not the same. The color red, for instance is always the negative lead of a thermocouple.

 

[cowboybob]

Graham,

Here's the zener pics I mentioned.

NOTE the current and voltage numbers. You can see how the zener's current increases (as its resistance decreases) with increased VS1 voltages, "bleeding off" the excess VDC will maintaining (pretty closely) the 5.1 VDC the zener is rated at.

View attachment 60948 View attachment 60949 View attachment 60950

 

[KeepItSimpleStupid]

Graham:

Don't read this unless you want to get confused even more. https://en.wikipedia.org/wiki/Tunnel_diode It's to just remind you that there are lots of diodes out there. There are even varactor diodes such as these: https://en.wikipedia.org/wiki/Varactor_diode. These are diodes in which the capacitance can easily be changed. And the DIAC: https://en.wikipedia.org/wiki/DIAC

Only casually look this over, but don't even try to understand them at this point.

 

[cowboybob]

Just thought to add this about the zener examples above:

Most circuits assume a fairly stable power supply. It would be a rare beast that experienced the voltage swings depicted in the examples I gave. As a result, the zener circuit would never be subjected that sort of voltage instability, and would be able to maintain its output very close to the specified level. In this case, 5.1 VDC.

 

[Muttley600]

Morning CBB

ok, I have been doing a bit of exploring this morning

Lets see if my understanding is any better now **broken link removed**

So basically we can use a zener diode to regulate voltage by using & staying within the parameters of it's reverse breakdown min/max, thus giving us a fixed voltage despite changing loads, they can be used as you were saying to operate a transistor to operate a larger current than would be possible still maintaining the required voltage, going even further we can add current limiting into the equation too, meaning that should current be exceeded putting the zenner outside it's parameters, the circuit would simply bypass the zener thus protecting it & shutting down devices, so my understanding now is that zener can be used as a voltage regulator as you explained, but not as a surge/spike protector.

so this would be a useful addition to my power supply box for my 5V requirement but a TVS diode would still be needed to deal with the spikes.

How's that?

 

[cowboybob]

Yes.

Within the confines of the zener's specifications, what you suggest is valid.

 

[Muttley600]

Yes.

Within the confines of the zener's specifications, what you suggest is valid.

trying to look at datasheets to get a better understanding it seems 5.1V zeners come at 500mW, which is not enough for 2A is it or have I totally misunderstood, if I'm right it would would have to go through a transistor to provide 2A, if not, I've totally missed what I'm trying to grasp

Edit: so now I have a datsheet that we can work with to try & understand this better, if I change the diode on the schematic you sent to a IN5231B, I can try & figure out resistors needed for a 2A load & figure out what I'm missing on calculating R1

so if I work on a 13.7 voltage - 5.1V I need R1 to be equivilent to 70 ohms giving 5.1V across zener, basically after playing I'm talking nuts again aren't I, it can't be done with a 2A load, I would have to reduce R1 to 5.8 to give me load which messes the V up, is this where the transistors come in

Please forgive me if I'm hard work **broken link removed**

ok, after another look I'm back to your test of IN4733 which looks possible **broken link removed** so basically I have learnt a bit more about zener diode but your already 5 million steps in front of me, lesson for today, listen to your tutor

where were we **broken link removed** can we try your test with 13.7V & see where that takes us

 

[cowboybob]

One of the problems with using a zener as a voltage controller is that at the higher current ratings, it takes a greater minimum current through the zener to get it into "steady" or specified VDC output mode. As the load draws additional current away from the zener, the available current for the zener to maintain its "steady state" output voltage is reduced, eventually to the point of no longer working as specified.

That's why a voltage regulator chip, like what you spec'ed out at the beginning, is a better choice for your needs. It can handle the additional current requirements of the load without losing the ability to maintain the appropriate voltage level(s).

 

[Muttley600]

New test:
8V = 4.52V / 53.61mA
10V = 4.92V / 78.11mA
12V = 5.13V / 105.62mA
18V = 5.46V / 192.98mA
24V = 5.63 / 282.58mA
even pushing it to 100V is only 6.42V, that seems sensible & when were talking mA, this is minute really isn't it = 1.44A off 100V

Which took me to my findings here, although I now understand we have to work within parameters

 

[Muttley600]

ok, being totally nieve has it's advantages here, because I'm guessing I have lots more possibilities until those ideas get shot down in flames **broken link removed**
So I see two possibilities

One of the problems with using a zener as a voltage controller is that at the higher current ratings

I'm thinking along the lines of 2A max current

it takes a greater minimum current through the zener to get it into "steady" or specified VDC output mode.

greater than what, a chip **broken link removed**

As the load draws additional current away from the zener, the available current for the zener to maintain its "steady state" output voltage is reduced, eventually to the point of no longer working as specified.

Isn't that why you need a higher working voltage than zener voltage

That's why a voltage regulator chip, like what you spec'ed out at the beginning, is a better choice for your needs. It can handle the additional current requirements of the load without losing the ability to maintain the appropriate voltage level(s).

failing the zener being the right product, is it possible to make one, it would be a lot more fun **broken link removed** afterall, they are about £4, I reckon we could make a schematic, buy parts & build one for about £150 including time **broken link removed** edit: ok, I accept at the speed I learn it might be £1500.00 **broken link removed**

 

[Muttley600]

ok, playing with sim & zener you suggested, with voltage at 13.7, R1 = 4.27 - R2 = 2.6 gives me a a 5.1V with Total A = 2.01A then Load A = 1.96A
so what your saying is it takes 0.5A to keep the zener in the reverse state

am I finally getting this?


So after looking at your sims again, the zener can keep a constant voltage but the more power you draw the more it takes to keep in that state, I'm starting to understand this zener concept aren't I

so what happens when you take the load out & it pushes the voltage above the normal working threshold

I think I've lost my way on what the zener is used for now *confused* nothing new there then, I need to go back & reread what we were originally talking about, I think I have the concept of the zener now (read-hopefully) so I'm hoping I can put two & two together & make four, whats the betting I come back with more questions **broken link removed**

just before I go back, so this zener could work between 4.84-5.35V, those are the min/max with PRV of 890mA, when I was looking at 2000mA draw, so this still couldn't do what I wanted without a transistor

 

[Muttley600]

Update: surprising what you can think of while feeding the dog.lol
Haven't read back yet, but in trying to relate the Zener to something that will make me remember it, I've taken a very narrow mInded view of it, once grasping the concept of what it does I can see that it could be used as part of a constant voltage supply in many applications, but the Zener is more of a part of a control rather than a single component solution

So there's more to this story your telling me

& understanding the Zener means breakdowns aren't always to be avoided if they are part of the overall plan

 

[KeepItSimpleStupid]

Here is a couple of simple circuits using a Zener diode: https://www.radio-electronics.com/i...ge-reference-diodes/applications-circuits.php

 

[Muttley600]

Got it, post #107
Part of trip system against overvoltage

Thanks KISS, that means Zener can be used for lots of different jobs, including what CBB had already mentioned in 107

Ok, think I have Zener sorted in my mind, what's next

 

[cowboybob]

Can't believe how much electronic parts costs you guys. Wow.

Anyway.

failing the zener being the right product, is it possible to make one,

here's a schematic of a LM317 adjustable Voltage regulator:

View attachment 60971

So, no. Unless you want to really beat yourself up.

so what your saying is it takes 0.5A to keep the zener in the reverse state

No. For the 1N4733, minimum reverse current is 49mA (0.049mA), although there is some slop around that value. As you can see, in my sim the zener holds 5.08VDC with 46.12 mA flowing through it. (EDIT: Ref post #302)

so what happens when you take the load out & it pushes the voltage above the normal working threshold

With no load (open circuit) the internal resistance of the zener rises (thereby reducing the current flow) to a level that corresponds to the resistance needed to maintain 5.1VDC. In the 12VDC supply voltage example, Z1C (and the current thru R1 as well) goes to 67.9mA, with a 5.21VDC value across the zener (and the remainder of the 12VDC, 6.79VDC across R1). This is the minimum current flow the system will draw with 100 Ohm current limiting resistor (R1) in series with it (as per the example schematics). This is the so called quiescent state, i.e., what the circuit draws with No load.

and on that note:

so this zener could work between 4.84-5.35V, those are the min/max with PRV of 890mA, when I was looking at 2000mA draw, so this still couldn't do what I wanted without a transistor

Well, Yes and no, but again, I think your misunderstanding the reason for using a zener vs. a voltage regulator "chip" such as the LM317 or any of the LM sereis (maybe not ALL).

but the Zener is more of a part of a control rather than a single component solution

t
Yes, in the present context. And Yes again. Nail that thought down.

A zener is designed to be primarily a voltage regulator: It is not "supplying" current to a load so much as "diverting" it so as to maintain the desired voltage across the load.

A device such as the LM317 maintains not only a constant voltage but also supplies a variable current depending on the requirements of the load(s). It is, as you can see, a pretty sophisticated device and it takes that level of sophistication to achieve this process.

In a word, you would not ordinarily substitute a zener for the job of a voltage/current regulating device.

Did I cover everything?

BTW. Did you get a chance to read through KISS's thoughts on the operation of your cigarette lighter device (Post # 287)?

 

[KeepItSimpleStupid]

The zener is a SHUNT voltage regulator. The controlling element (The zener itself) is in parallel with the load. Regulators like the LM317 is a SERIES regulator where the controlling element (transistor(s), FET(s)) are in series with the load.

I worked on a HV DC power supply, ~15 kV at 1 Amp in which a tube/valve was used as a shunt regulator.

The problem with the zener is temperature dependence and it's the smallest at 5.1 V that's why that voltage is special. The zener has largely been replaced by the bandgap voltage reference https://en.wikipedia.org/wiki/Bandgap_voltage_reference
for a precision voltage source.

With power supplies, there are usually a couple of specs. Line regulation and load regulation. Line regulation is how the output changes with input voltage changes and load regulation is how the output changes with load changes.

 

[Muttley600]

Can't believe how much electronic parts costs you guys. Wow.

It's cheaper than fuel at £1.36 a litre for motorbike **broken link removed**

here's a schematic of a LM317 adjustable Voltage regulator:

View attachment 60971

**broken link removed**

So, no. Unless you want to really beat yourself up.

ok, you sold me, that's a bad idea **broken link removed**

No. For the 1N4733, minimum reverse current is 49mA (0.049mA), although there is some slop around that value. As you can see, in my sim the zener holds 5.08VDC with 46.12 mA flowing through it. (EDIT: Ref post #302)

ok, need to go back to sim for that one to make sure I fully understand it, can see where your putting your meters so I can relate it to process I used to try & understand **broken link removed** big miss on my part there **broken link removed**

With no load (open circuit) the internal resistance of the zener rises (thereby reducing the current flow) to a level that corresponds to the resistance needed to maintain 5.1VDC. In the 12VDC supply voltage example, Z1C (and the current thru R1 as well) goes to 67.9mA, with a 5.21VDC value across the zener (and the remainder of the 12VDC, 6.79VDC across R1). This is the minimum current flow the system will draw with 100 Ohm current limiting resistor (R1) in series with it (as per the example schematics). This is the so called quiescent state, i.e., what the circuit draws with No load.

That makes more sense

Well, Yes and no, but again, I think your misunderstanding the reason for using a zener vs. a voltage regulator "chip" such as the LM317 or any of the LM sereis (maybe not ALL).

I think your right

Yes, in the present context. And Yes again. Nail that thought down.

Will do, firmly etched in my brain

A zener is designed to be primarily a voltage regulator: It is not "supplying" current to a load so much as "diverting" it so as to maintain the desired voltage across the load.

A device such as the LM317 maintains not only a constant voltage but also supplies a variable current depending on the requirements of the load(s). It is, as you can see, a pretty sophisticated device and it takes that level of sophistication to achieve this process.

In a word, you would not ordinarily substitute a zener for the job of a voltage/current regulating device.

Did I cover everything?

So does that mean zeners would norally be used with a fixed load as opposed to varying loads or have I missed again

Thanks CBB

On the bright side it looks like my box is getting more complicated, that can only be a good thing.......right **broken link removed** cause that's gotta mean more learning **broken link removed** I'm slow but hopefully I'll get there

 

[Muttley600]

The zener is a SHUNT voltage regulator. The controlling element (The zener itself) is in parallel with the load. Regulators like the LM317 is a SERIES regulator where the controlling element (transistor(s), FET(s)) are in series with the load.

you started it, so now expect numpty questions from the newbie **broken link removed** so I've seen 'in series' & 'in parallel' used, what does that mean in plain english

With power supplies, there are usually a couple of specs. Line regulation and load regulation. Line regulation is how the output changes with input voltage changes and load regulation is how the output changes with load changes.

video covered that briefly but that makes sense, so for power supplies you need to account for both, even more complicated when trying to design a dual voltage supply with different loads dependant on whats hooked up or am I making hard work of understanding this **broken link removed**

To be honest I've never given this much thought when attaching toys to bike

 

[Muttley600]

ok, well looking for LM317 & seeing it was 1.5A, I had a nose & found these 2A ones, whats the difference, they all seem to do the same job **broken link removed**

NTE1934

LM2592HV

LM22680

 

[Muttley600]

ok, need to go back to sim for that one to make sure I fully understand it, can see where your putting your meters so I can relate it to process I used to try & understand **broken link removed** big miss on my part there **broken link removed**

Thanks CBB, it all makes sense now

**broken link removed**

oh, look there were instructions to leave R1 & 2 alone, does anyone read instructions these days **broken link removed**

It'll get me into trouble one day won't it **broken link removed**

but in my defence I did do the test first **broken link removed**

hold on a sec, isn't 49mA 0.5A **broken link removed** I can see where I'm getting confused, there isn't 100mA in a A, there is 1000 **broken link removed**