Author Topic: Simple Shunt (Read 14493 times)

windstuffnow · « **on:** November 10, 2005, 02:03:40 AM »

I'm trying to come up with a "bare bones" shunt that will basically keep the batteries from cooking... will this work?

It actually keeps a small battery at 14.6 volts but I'm not sure it will last... The sheet shows the base voltage at 5 volts should I put a resister between the Zener and base to hold the voltage down?

Of course my knowledge of electronics is... well... lacking to say the least... feel free to updade the drawing or give me some pointers...

.

adelaide · « **Reply #1 on:** November 09, 2005, 07:54:37 PM »

if it is working it is SIMPLE just add as much heat sink u can may help reliabilty or 2 and work out ur peek amps and see if in specs still ,how may amps u got in and out handling?

ghurd · « **Reply #2 on:** November 09, 2005, 08:06:51 PM »

I think its going to take killer part$, in the watt$ department.

Mosfets might be better? I like mosfets.

I'm working on about the same thing, with mosfets in stages.

G-

windstuffnow · « **Reply #3 on:** November 09, 2005, 08:53:51 PM »

Hi Ghurd,

You know I tried an IRF510 and a IRF840 and couldn't get them to work right. I don't know if it takes more voltage to turn those on or what.

Since I'm not real electronics savy the terminology of the pin outs are quite confusing. The 3055 NPN call them Base, collector and emmitter where the Fets call them Gate, source and drain. I'm assuming the "gate" and "base" are the input sensor (on off switch ) where the collector- emmitter (in out) is the same as the source and drain is that correct? On the Fets I couldn't get the gate to gate ( turn it on). As you can see when it comes to electronics I'm just plain ignorant... I can identify components somewhat and manually discharge capacitors with my tongue and tell you when there is high voltage on line by touching the bare wires... Ok just joking... I said I was ignorant not stupid !!

This unit will only be diverting 1.5 to 3 amps for the most part. I just needed a simple way of holding the battery voltage at a certain level when I run tests in the tunnel.

.

ghurd · « **Reply #4 on:** November 09, 2005, 09:26:57 PM »

If you are using RatShak parts, diagrams, or pin-outs, they are often just plain wrong.

More so with IRF (RS. #IFR510?) numbers.

Connecting the parts as shown on the package will ruin them.

Same with a lot of their TO-92 parts.

With the IRF510 and 840, I use '12V' and no resistors to turn them on (they'll take 20V). They need a high ohm resistor to bleed the Vgate, or they can float or stay on, even without an Igate.

And they have a bit of a ramp up voltage. I am figuring the ramp up voltage to about MPPT the load on something I'm trying now.

There is a published circuit that does what you want. I can't find it.

redock, redrock, redoc, redok, red-something dotcom.

A huge page.

(He has a tracker that runs from LEDs triggering transistors too)

A couple tweeks and his "simple shunt" should work.

OK. Found it. Shunt1. It'll take some time to load. Make some coffee now. 75% down the page.

http://www.redrok.com/electron.htm

G-

Nando · « **Reply #5 on:** November 09, 2005, 09:35:35 PM »

SIMPLICITY IN THIS CASE will destroy the battery or the SHUNT.

You really need an amplifier to drive the transistor or the MosFet to accurately maintain the battery voltage well regulated.

Due to the low gain of this circuit the accuracy is around 0.25 to 0.5 volts.

The Mosfet driving the 1.2 resistor is best.

If you are interested in the circuit send a note to me to make a GIF file in my profile.

Also, let me know how many amps shunt you may need.

Regards

Nando

kell · « **Reply #6 on:** November 09, 2005, 11:08:30 PM »

That diagram is all mixed up.

You have the collector and emitter connections reversed.

The collector is the middle pin (and tab). Base is the pin on the left, emitter is the pin on the right.

On a shunt you would connect the collector to the battery positive -- but not

directly; much better to put a load there (between collector and B+) to dissipate heat. The voltage drop across this load (power resistor) must be at least a couple of volts less than battery voltage when maximum current flows through the shunt.

To shunt 20 amps, you could use a 0.6 ohm power resistor, which would have to dissipate 240 watts (!!) and would have 12 volts across it. The transistor in that case would have roughly 3 volts across it, and would have to dissipate 60 watts. Enough to burn out your transistor unless you have a very big heat sink and a muffin fan.

These are numbers just to illustrate. You have to do the arithmetic for your application. But you get the idea about how hot things can get.

Emitter (the pin on the right) must go straight to B-, since you are using the base/emitter voltage as a reference. Your shunt voltage will

be the base/emitter voltage plus the zener voltage. Zener anode connects to base, zener cathode goes directly to battery positive.

Base/emitter is just a diode voltage drop, nominally 0.7 volts, depends on current and temperature. So a 14 volt zener for example would give you a 14.7 volt shunt.

You also have to consider base current. Take the shunt current, and divide by the transistor's gain at that current to find base current. To find out the heat dissipated by the zener, multiply base current by the zener voltage.

windstuffnow · « **Reply #7 on:** November 10, 2005, 09:25:46 AM »

Hi Kell,

I changed things around as you said, I looked at the sheet but connected the E and C backwards... pin out dislexia ;o)...

Also, looked at the Shunt1 from redrok and it looks like I almost had it. So I added the 3 diodes ( not sure why there there ). I'll test the unit this afternoon to see if it holds the voltage down on the battery during a quickie test.

Thanks for the input and advice !

.

ghurd · « **Reply #8 on:** November 10, 2005, 10:14:57 AM »

The 3 diodes forward voltage drops are to bump the voltage up past the 12Vz.

Like 12Vz + (3 diodes x 0.7) = 14.1V

A 13.8 or 14V zener could replace the whole mess.

I'm curious how it works for you, and what you used for Q1.

G-

windstuffnow · « **Reply #9 on:** November 10, 2005, 03:40:17 PM »

Well Ghurd,

So far it doesn't work at all. It held the battery at 14.6 the way I had it before but I'll be darned if I can get it to work in this different configuration ( like the Shunt1 on redrok ). It's getting frustrating to say the least.

I can disassemble a 400 turbo leaving 1200 parts + on the bench scattered around and reassemble it with new components and put it back in the car by the end of the day working great... or take a pile of steel and build a chassis for a 23T roadster in the same day... in my day that is... take a transistor and a diode and make it divert energy from a battery.. 3 days and counting... It seems so simple... you electronics guys are laughing I'm sure... ok have your fun...

.

ghurd · « **Reply #10 on:** November 10, 2005, 05:05:53 PM »

The Q1 could be cooked?

Honestly, not sure how great those kind of shunts are. Never built a shunt regulator.

(Solar is easier!)

I'd be tempted to tell you to take out the 3 regular diodes, and try it with a current limited 18V power supply. Vce on =4V, so the mess of diodes may be better replaced with a 10V zener? 10+4=14V. But I like majic smoke.

Ideas from the gurus?

I won't tell you to try that.

G-

Opera House · « **Reply #11 on:** November 10, 2005, 05:30:05 PM »

You should look at using a three pin LM 432 amplified zener. The adjustment pin can monitor the + voltage via a pot voltage divider to minus. The zener will basically turn on or off. Use an LED and it makes a great voltage monitor! For a shunt just drive a transistor or a fet. Stagger the set point on a couple of these and you can have additional resistors every 20 mv. Turning a fet or transistor partially on is a sure way to kill it.

Opera House · « **Reply #12 on:** November 10, 2005, 05:32:55 PM »

TYPO.......LM431 Google the data sheet, there are examples.

windstuffnow · « **Reply #13 on:** November 10, 2005, 05:51:41 PM »

I did get it to work, The Shunt1 shows a 5 ohm resister and I'm using a 1.2 ohm. The voltage was going over 16 volts, it may have worked in a higher range. I removed one of the diodes and it dumps at 14.5, with only one diode inline it keeps the battery at 13.8. The Tip3055 does get fairly warm though, I have a very small aluminum heat sink on it right now but I plan to mount it on a 3/8" aluminum plate which should help. I think I've got it... finally.

.

ghurd · « **Reply #14 on:** November 10, 2005, 06:45:34 PM »

So use the LM431 to replace the zener?

I'm using a 100ma TO-92 fet that is half on quite often, with a 50ma load. Works fine. CDS cell controls the fet, fet controls LEDs.

Should I expect it to fail soon?

G-

dinges · « **Reply #15 on:** November 10, 2005, 07:40:23 PM »

Hi,

It might work if you keep 2 things in mind:

In series with the Zener SHOULD(!!) be a resistor to limit max current to the zener to, say, 10mA R=(14,6-12)0,01 = 260 ohm; 270 ohm is a standard value that you could buy.

The resistor goes from the kathode of the zener (where the stripe is) to the collector of the 2n3055 (where you connect the +12V). Parallel over the zener you should put in an electrolytic cap of about 1 to 10 uF /25V (or bigger; voltage rating should be higher than your 12V, capacity isn't very important here).

Hope the ASCII-schematic survives & shows properly on the board...

C E

>14V ---------\ ---------------- Vout/regulated.

| \ / (emitter)

| ----

| |

| |

R(270ohm) |

| |

-------*--------------

--- (stripe=kathode) |

/ \ zener | +

--- = electrolytic capacitor (10uF/25V)

| |

| |

gnd gnd

It's basically a voltage regulator. Your voltage will be: Vzener+0,7V. So, if you need 13,8V, your zener should be 13,8-0,7=13,1V (13V is a standard value).

Your voltage will then never be higher than 13,8V at the output.

Beware: at larger currents & higher voltages, the 2n3055 has to dissipate all the power as heat. You may need a heatsink!

My tip: find a HAM nearby and show him the schematic/your problem. This is elementary stuff for HAMs (radioamateurs); I am one, and it's one of the things I build without thinking over too much; every project I build needs a powersupply, and this is one way to do it.

Better yet: take an 7812 Voltage regulator IC (has three legs, just like your transistor), the 1A version. Put one or two diodes in series with the ground leg, and your output voltage rises from 12V to 12,7V (with one diode) or 13,4V (two diodes) or 14,1V (three diodes).

My & other's explanations may not mean much to you; in that case, find a HAM or electronics guru in your area. (better yet, become friends with him, so he can build all your electronics control projects for your windmills ;-) )

Good luck,

Peter,

The Netherlands.

A

windstuffnow · « **Reply #16 on:** November 10, 2005, 10:18:53 PM »

Thanks Peter,

I did a copy,paste, print of your reply to see if I can make heads or tails of it. The ASCII drawing is kind of difficult to follow. I'm not sure I follow about the placement of the cap. I probably have everything you've added to the diagram resistor,cap etc to complete it. I have the unit up and running, just need to put a better heat sink on the 3055. I would like it to last a while although the tests are usually short and no more than 2 amps that need to be dumped during the tests.

I could cure the problem by putting a bigger battery on the test stand and the 1.5-2 amps wouldn't make much difference. The small 5Ah battery that I'm using will easily run over 16 volts during a test.

Thanks for the input, I'll study it over and see what I can come up with!

.

Opera House · « **Reply #17 on:** November 11, 2005, 04:12:33 AM »

The LM431 is a precision amplified zener which is adjustable from 2.5V to 35 volts and can handle about 100ma. It can be used anywhere a normal zener is used and allows you to adjust the voltage. The real beauty is that this is just a three lead device that operates much like a precision voltage reference and an op amp comparitor to turn a transistor or fet totally on or off. In your zener circuit, as the voltagestarts to exceed the zener voltage the transistor starts to turn on. The power the transistor dissipated is the product of the current and the voltage across it. A couple volts and amps is a lot of power and the transistor often has to dump more power than the resistor. That will bring a quick death.

windstuffnow · « **Reply #18 on:** November 11, 2005, 07:55:36 AM »

I just looked at the data sheet for that and it looks like it would make a real nice quickie shunt regulator. They had a sample circuit on the sheet for exactly what I'm doing. I may try that next time I run to the electronics store. Thanks for the tip!

.

ghurd · « **Reply #19 on:** November 11, 2005, 08:02:32 AM »

How about a link for the sample circuit?

finnsawyer · « **Reply #20 on:** November 11, 2005, 08:42:27 AM »

After reading the comments here, it occurs to me that we need an easy program for drawing schematics. does anybody out there know of such a program available in the public domain? A simple drag and drop type deal, where the symbols are available in an easily accessed library. During the years of the commodore 64, I wrote such a program, but I used key strokes to drop in the the various components, and the cursor keys to draw the connecting lines. I also had a program to draw circuit board layouts. This was, of course, somewhat primitive. Come to think of it, if I had a way to convert the diagrams to JPEG, I could go back and use the 64. Or I could photograph them. Kind of a circuitous route, though.

windstuffnow · « **Reply #21 on:** November 11, 2005, 12:08:18 PM »

Well, I got the circuit working on an experimental board. Soldered all the components to a perf board, came out quite nice looking... took it out and connected it and the battery voltage went way over 16 volts, I by-passed the two diodes and it maintained 15.5 volts. The only thing that was different was the 270 ohm resistor in series with the zener diode.

I cured the problem completly... I went inside and brought out my 115Ah RV battery and threw the circut in the trash. Works great !

I'll leave the electronics projects to the guru's...

.

monte350c · « **Reply #22 on:** November 11, 2005, 01:17:22 PM »

Hi Ed,

Ouch!

Sorry I didn't have anything to add here, there are others with a lot more experience than I. Glad to hear the big battery cured it. You can always put a load on the battery that's around the same size as the alternator will be putting in. Like an 1157 or two. More if the voltage goes up.

On the circuit drawing business, there is quite a nice program here: http://www.expresspcb.com/ExpressPCBHtm/Download.htm

The Express SCH will do very easy and professional looking drawings. (Of course whether they work or not is up to you!) It's free, the idea being that once you get something you like, the company will be happy to etch printed circuit boards for you.

Ted.

ghurd · « **Reply #23 on:** November 11, 2005, 01:26:08 PM »

Simplicity at it's finest!

Don't feel bad! 80% of the stuff I try from the internet will not work for me. Not at all. Not even a little.

Bruce S · « **Reply #24 on:** November 11, 2005, 01:32:13 PM »

Ed;

Not sure if I'm too late but here is an easy way as well. By attaching this to a aluminum plate will allow it to handle to 2 amps.

I am pretty sure the main reason you had problems with the others was no current limiting resistor (R1 for the circuit below) and you where sending the 3055 into a current/thermal overload, hence the high voltages( other than the pins in the picture being shown backwards, or the diode backwards).

I like the adjustable ones, as they are perfect for making 6 volt lights work with 12 v batteries without the coffee heating effects of using a resistor or diodes.

This can get too hot to hold in your hand if you go much above the 1 amp. however it is a very efficient supply.

Hope this helps in the future.

PS any diode works just needs to be able to handle an amp.

Bruce S

dinges · « **Reply #25 on:** November 11, 2005, 03:32:46 PM »

Hi Ed,

I understand you don't understand my drawing; I don't understand it myself anymore as it shows on the board;

I was going to make a quick drawing in Autocad, until I did a search on the internet (search for '2n3055', 'zener', 'power supply', 'regulated', etc) and there were the schematics, free to copy & pase ;-)

best link I've found, schematic with explanation:

http://www.electronics-tutorials.com/basics/power-supply-regulated.htm

HOWEVER:

I realized too late that you need a shunt-regulator; the schematics I've drawn & linked to are regulated power supplies: whatevery you put in (DC from 15 to about 35V) is converted to e.g. 12VDC (or 5VDC, or whatever, depending on the value of your zenerdiode). A shunt regulator that you need has to dump a load in something else than a battery.

Hmm, am thinking as I'm writing this:

a regulated power supply will work for your application, because your shunt load in this case is the 2n3055 and its heatsink! All the excess power (any volts over, say, 13.8V) get converted to heat in the 2n3055. Just what you want, perfect for your application, but not for 'real windmills', since in that case you would have to dump very much more power than the 2A in your case (10A would be possible with a 2n3055 that's sufficiently cooled; I think they can dissipate 150W, from memory; don't know about the TIP3055, but it'll probably be less (different housing of the transistor: 2n3055 has a 'TO3' house, that has very low thermal resistance, thus can be cooled efficiently. TIP3055 is similar to a 'TO220'-house.

To make a long story short: building a regulated powersupply that puts out 13.8V at 2A or more WILL work in your case. You won't even need a dumpload (your 1.2ohm resistor, or a lamp) because your TIP3055 is the dumpload that dissipates excess energy.

If you need more info, don't hesitate to ask!

dinges · « **Reply #26 on:** November 11, 2005, 03:54:15 PM »

Hi Ed,

Forgot to upload the schematics; here goes: two different ones I've found, but you'll notice the similarities.

Notice how uncritical the values of the components are: elco's should have the right voltage rating (25V or higher), but exact capacity is less important; anything halve or double that value will work (probably 10* or 1/10 the value still works). The resistor is 3* my value (680ohm vs. my 270ohm), doesn't matter.

In your case, you don't need the bridge rectifier and transformer; if you do include the bridge, you will never have to worry again about connecting the right polarities: it doesn't matter if you accidently reverse polarity (+ vs. - reversed), the bridge-rectifier makes sure the actual regulator sees correct polarity.

I would use the 2nd schematic, it's just as I've been tought to do this job.

Your minimum requirements are:

-2n3055 (TIP3055) transistor

-zenerdiode (Z1)

-resistor in series with the zener (Rs)

the 'frivolities' that I'd personally add, but which it'll probably work without:

-capacitor over the zener (only drawn correctly in the 2nd schematic) (C2) (it would probably work without this capacitor, but you output might be noisy; an issue for a normal power supply, not for your application.

-bridge rectifier, to prevent wire mistakes from producing smoke.

-a fuse (5A? 10A?)

-C1 and C3; but are not needed for you. Your 'C3' is your battery, a VERY big capacitor.

-don't use the Rp (1k); it will slowly (14mA) drain your battery if the circuit is left connected to the battery (consider it like a load, a lamp that doesn't produce light :-) )

- the amp and voltmeters I never add. You might, it's up to you.

Like I said, the schematic is for a normal, regulated powersupply. This one's designed according to the rules ('good engineering practice'). Your bare bone's version would work with the 3 items (minimum requirements) that I mentioned previously (transistor, zener, resistor) (C2 isn't strictly necessary for your application, as I incorrectly stated before)

Like I said, you decide the luxuries you want. If it were to run for hours on end, unattended, on 'mission-critical' applications, go with the 2nd schematic. If it'll only run for a few minutes at a time, attended, with finger always near the 'emergency stop' button, you may get away with the bare-bones minimum (3 components).

Good luck & let me know if you need more help,

Peter,

The Netherlands.

(who's glad he can help out; I owe my understanding of 3phase-stuff to your excellent website!)

windstuffnow · « **Reply #27 on:** November 11, 2005, 04:12:14 PM »

I guess I was under the impression that the transistor or Tip3055 in this case, was basically like a relay. You introduce voltage to the gate or base and the current will flow. The 1.2 ohm resistance was actually a coiled piece of nichrome wire, I assumed would be the part that heated up or dump load. Although it does get warm when it was working the transistor did get a bit warmer. The Tip3055 was rated at 10 amps (15 maximum ) so I assumed it would handle a 2 amp load without any problem. With the exception of the heat sink I was using which I would have changed if things worked the way I thought it should.

I've put together other circuits in the past that were a bit more complex than this stupid simple thing and usually, not always, they worked out fairly well.

Since my frustrations have subsided I'll get it out for one last go at it... I mean really... I figure I have upwards to 600.00 labor into it if you count most of the time I've spent on the darn thing and of course 2 bux worth of parts. If I don't count the time then it doesn't seem so bad. The time wouldn't matter if it ended up working and I learned something from it but at this point I feel the only thing I've learned is not to build another one... at least not like that one!

Lifes little challenges...

.

dinges · « **Reply #28 on:** November 11, 2005, 04:24:56 PM »

Hi Bruce,

I wanted to show this schematic to Ed too, but didn't want to confuse him anymore than I already did ;-)

Your circuit would work very nice too. The max. current of the LM317 is 1.5A, Ed said he needed a bit more. Plus, if this circuit goes into 'overcurrent protection', it drops the load, causing your windgenerator to speed up. This is perfect for a 'normal' voltage regulator, but not for a shunt-regulator for windapplications.

So, in this case I think Ed would be better of using his TIP3055, zener and resistor. Simple & sure to work, unless he makes wiring mistakes.

Ed's solution is probably even better: a bigger battery that's harder to 'overcharge'. Simple & sure to work, if you have the battery. We all have different means and capacities, and what works best for me (like the shunt-regulator) may not be best for Ed... I, on the other hand, have only a few small batteries, so Ed's solution isn't mine :-)

As far as building things from the internet goes (80% or so not working). My experience is that ANYTIME I build something exactly according to someone else's plan but don't understand how/why it works, I fail. When I understand how & why something works, I usually add/change things. Sometimes it works, sometimes it doesn't, but then I have the knowledge to make it work.

My generators are never exact copies of someone else's design; if you understand how/why they work, you can play around a bit, change things, and it'll still work (or maybe even work better for your specific application).

I consider this forum, books and the internet to be a 'source of ideas' and to give me knowledge. I never consider a plan I've found to be a surefire blueprint that'll work right first time. Realizing this (when I was about 14, started with building electronics stuff that never worked, but didn't give up, started studying & understanding electronics) makes the difference between being a slave or a master of electronics (or car-technics, or whatever). Without the right knowledge & just building things 'according to plan', you can only hope it works; if it doesn't, you don't know why. Very frustrating...

To get back to Ed's problem: in your original schematic, the zener didn't have a series resistor to limit current. This would mean that the poor little zener would try to dump ALL excess power above 14V (say,16V-14 = 2V; at 5 amps this would mean 10W). Now you probably used a 0.3W zener (1W maybe?); trying to let it dissipate 10W will not work, it'll blow the zener like a fuse (or perhaps cause it to internally short).

BTW, if you had a REALLY big zener (say, 20-100W) of a value of 13.8V or thereabout, you could use it as a shunt load for windgenerators! Just connect it over your + and - wires like you'd connect a lamp, and you have instant protection. Those zeners do exist, but I've never seen/had one. Probably expensive too. The transistor (2n3055) acts as an 'amplifier' for the zener; you can use a small zener, but in combination with your heavy transistor, it'll work as a heavy, big zener! A bit simple explanation, but not too far from the truth.

Hmm, better stop typing, this answer is getting way too long...

Succes,

Peter,

The Netherlands.

TomW · « **Reply #29 on:** November 11, 2005, 04:51:36 PM »

flux;

Yes and go one better slap it online so it is useful in the browser so it wont matter what type computer you use.

Cheers.

TomW

windstuffnow · « **Reply #30 on:** November 11, 2005, 06:54:44 PM »

Hi Peter,

I went back to it, by-passed 1 diode and it dumps at 15.5 volts and bypassing the resistor its back to 14.5. The small voltage drop throught the resistor made a big difference, as well as the extra diode. It's almost back to the original without the crossed connections but working... for how long? So now it has the zener with 1 diode to the base. I still have to make a heat sink and hope it holds up. It's only used for short runs of 3 to 5 minutes or less. I hate to lug the big battery over to the shop everytime I want to run some tests so the small one makes it easily moved and quite portable.

Anyway, thanks for all the help, I'll study over the schematics and see if I can attempt a better one. I may try to use the LM413 on one to see if its easier to get it to work... I like the idea it's somewhat adjustable.

.

dinges · « **Reply #31 on:** November 11, 2005, 07:06:49 PM »

Hi Ed,

Understand your feelings. When frustrated,do something else until you get enough enthusiasm to give it another try.

Like I said, the 3 parts you need you already have. Connect them (not even PCB is needed) and ready. My problem with these simple things (power supplies) is that they're so simple I won't bother drawing a schematic and build from that, but that I build from memory. A couple of weeks ago, I built a power supply based on a 7812 like that, without schematic & accounting for which components and links I had already made. After 15 minutes of soldering it was ready but didn't work. Took another hour(!) until I found out I hadn't grounded the middle connection of the 7812; consequence: input voltage was output voltage--> lots of expensive electronics damaged...

Like I said, follow the schematic, glue components together and give it a go. When it works, you can buy me a drink ;-)

Transistors can work both as 'switch' and as analog amplifier. In your case, the 2n3055 shouldn't work as switch but as analog amplifier (amplifies zener voltage, from low current to a higher current). FETs (with their gate, drain and source) operate quite differently. I've experimented with them for the first time a couple of months ago, and I like them (easier to use than transistors in some cases).

I am giving one last detailed description on how to build:

connect kathode of zener to base of 2n3055; connect base of 2n3055 to collector via R=270 ohm (or 330 or 470 or 680, who cares). connect anode of zener to ground.

That's it, don't even need a schematic!

Connect collector of 2n3055 to + (plus) of your windgenerator; connect anode of zener (gnd) to minus of windgenny. Connect - of batter to ground; connect + of battery to emitter of 2n3055.

Switch on windtunnel and admire.

Hmm, I've wasted more time explaining and typing all this than if I had simply built you the d*mn thing and mailed it to you... 5 minutes building, including finding the components...

I've made one mistake in a previous post: your output voltage will be zenervoltage MINUS 0.7V (B-E diode inside your 2n3055). So for 13.8, use a 14V zener; this gives about 13.3 V output (you could put another diode (1n4148 or something) in series with the zener; this would compensate for the diodeloss in the 2n3055; then output voltage would be (almost) exactly your zener voltage. Connect kathode of 1n4148 (or 1n914 or other si-diode) to kathode of zener; (so both 'striped sides' are connected to gether, back-to-back)). Put this new 'module' where your single zener diode used to be in the schematic.

Let us know it goes,

Peter,

The Netherlands.

Drives · « **Reply #32 on:** November 11, 2005, 07:52:22 PM »

Ed:

Hope this helps. Just remember to heatsink the transistor very well. Additionally, I would use a 12vdc cooling fan to cool both the zener and transistor.

News:

Author Topic: Simple Shunt (Read 14493 times)