Contribute a simplest led circuit

Hello cnpower

Good to see you back at CR4 Forum.

Thank you for your complex circuit.

The simplest LED circuit is a 1.5 volt dry cell, in series with the LED, no other costly parts are required.

Kind Regards....

I guess there someone out there will laugh at my complex composition but havnt thought of you.

look carefully at the led. its high light white led, not ordinary led. do you know how much voltage drop it is?

you will not say such words and will dont laugh at our chinese save energy lamp products.

Hello again, cnpower

You did not specify any LED at all, just a LED.

I trust you were not offended by my reply above.

It's very important to correctly specify all parts, otherwise in a Contract, you or your employer may lose large amounts of money.

Kind Regards....

look at pic of led with w. enlarge pls.

the circuit is for everyone out there who like diy, not for making money.

so nothing will be lost. don't worry.

I dont think I will make huge power dissipating mistake.

Its a neat little circuit and quite self explanatory, a good way of dragging the most power out of a single cell.

White LED's typically have a 3.4 Fvolt drop at 25 mA dirve current

Hello madness

I know that, but the type of LED was not specified in the original post.

The circuit as drawn by cnpower is an elegant solution, which will cost some $$.

The easiest way requires very little, the LED being a Red one, but does not run a white LED very well, of course.

Kind Regards....

cnpower,

I like your circuit - very elegant. I will probably breadboard it and play around with it. But, admit it; Sparkstation got you on not specifying the L.E.D. type and forward voltage drop!

I'd give him (cnpower) partial credit...

On the original drawing, there is a black trapezoid that was probably a lower case 'w' in the original drawing, just above the 'led' (the LED is also in lower case, but is definitely readable). It is so small that even after enlarging my screen several times, it still is just a black trapezoid.

It's too bad we can't post pdf files, which can be enlarged to improve resolution.

Of course the 'w' could mean white, but I'm sure there are other possible interpretations...

Dick

no doubt its w

originally it was wroten by chinese" 白光二极管" can you see these chiese characters?

I change it into english. so that everyone can read it.

the words size is equal .

Yes, I can see them, but of course they have no meaning to me. Just in case, here is a screen dump of what I see:

Do the characters appear the same here as they did originally on your screen?

Dick

you screen can display chinese code?

what software are you using?

It's a Macintosh! Macs have had Chinese as standard for many years, and also have Japanese and Korean, among many others. Here are the standard sets available on a 5 year old Mac using a two or three year old operating system (OS 10.4):

I just checked on a newer Mac - it has added Zhuyin to the traditional list. It doesn't matter what software; I happen to be using FireFox (version 2) on this Mac, but Chinese looks the same on the newer one using Safari, even though the CR4 toolbar is missing in Safari.

Dick

There are too many input ways you are using in your machine. most of them are useless. Like most of chinese, I m only using Pinyin or intellgent pinyin input way, which is used by more than 96.9% population.Cangje is old one for taiwanese.

chinese code has many kinds, like big-5, which is widely using in Taiwan or traditional chinese characters. we ususally use gb2321 for our simple chinese characters display or utf8 for general.

In ourmain land, we generally use PC, Apple machine is ususlly using in media making industry. for example, ad, tv, filmmaking etc.

I hvnt used such machine only but appleII many years ago. curio

A simple circuit (that keeps working) would be a LED is series with a current limiting resistor across a 1.5V cell.

The resistor is not costly.

Looking at cnpower's circuit it's obvious he knows what he's doing.

How critical is the turns ratio? Standard laminated core? How big is the transformer?

Interesting circuit!

Hi,

I am a Mechanical guy and have no knowledge of electronics but would love to dabble in electronics as I see combination mech+electronic is very powerful.

Would you be kind enough to go one step and explain how your circuit works and name the components so that we can buy them from a shop?

this is a simple circuit, we generally call it transformer feedback type circuit. its from very old time. it also has form of boost.

very easy to vibrate . it can be used as flashlight, in fact, most of appliance are use it.

when you change transistor and supply you can get a dc power supply.

from 220ac to some dc valuse say, 5v, 12v, 36v etc....

of cause the turns of tansformer and core has to be changed as well.

from now on you have become an senior engineer

Is C3 required? You will get pulsed light but the peak intensity will be higher and I am assuming that the frequency is high enough that the eye won't notice. I'm thinking you can simplify further by deleting C3.

wow, shaolin gongfu is very great!

you can try to cancel this c3 and d1 to reduce cost. but the led will work in pulse mode very much not as same lighting as they are existing.

in fact, the type of d1 in pic is not good. it has all too higher votage drop to reduce efficiency. you can use a schootch diode replace it. so that you can get a higher efficiency.

and the transistor can be replaced by 9013 else, but the specificatoin of 9013 is lower than 8050, but they have same price.

Do you know the East German car Trabant? It had a 6 V electric system and we used similar circuits to power 12 V radios.

I like your circuit.

From this circuit, you can deduce mny application.

rise voltage you can get an ignition fo r your motorcar or truck.

you can add a regulator to become a true real power supply of dc.

oh. dont forget change paramters and the transistor.

cnpower,

I breadboarded your circuit - very robust design, it worked right out of the box even with some component changes. I did the initial power up with a 150 ohm resistor in place of the LED. It settled right to 3V.

The inductor is a Miller torroid choke (around 10-20uH I think) It had 13 turns, so I added another winding with 9 turns.

The transistor is a 2N3904 and the two LEDs are in series to give the same V drop as a white LED.

Hello LG_Dave

Great to see the picture - "A picture is worth a thousand words".

But I cannot actually see the "breadboard" that you say you used.

Kind Regards....

Sparkstation,

"breadboard" is used here as a verb, not a noun. "Prototype" would have worked as well, but I think in terms of breadboarding when I am doing electronics. This is the "dead bug" method - where the parts are simply hung together by their leads. Don't, of course, attempt this at higher speeds or current levels, or where shorter signal paths and a ground plane are necessary.

LG_DAVE

Hello again LG_Dave

You're preaching to the converted.

I made my first crystal set back in 1950, hand-wound the coil, located the correct point on the galena crystal, and more, ever since.

In those early days, before I was old enough to use a soldering iron (we only had a single power outlet in the house and the non-electric soldering bolt was heated via a kerosene blowlamp), I did use a board, with woodscrews and washers to hold the connections and parts.

I did not get the chance of using my Mother's breadboard, and instead used the end out of a wooden banana box, so my early efforts would have been the banana box end method, I suppose.

Yes, I do realise that your picture shows the "dead bug" method, which I often do myself, when in a hurry to see if the circuit is going to work....or not, rather ugly, but quick and effective.

Kind Regards....

Sparkstation,

I made my first crystal set somewhat later than you did - 1957. I was able to purchase a diode (germanium) at the radio repair shop and so did not use a galena crystal. I also had a soldering iron available - a 300W metal workers one, and a roll of acid core solder. And yes, a board, wood screws and washers.

LG_DAVE

wow great!

try to reduce your core so that it can reduce your cost more.

cnpower,

here is a much smaller inductor - a ferrite bead, approx 5mm dia x 10mm long. This time it came up at 3.6V - Probably the # of turns is off. The cell V is down to 0.9V and the circuit still works.

LG_DAVE

I have been playing around with this sort of stuff since white leds became available- the trouble with this & other driver circuits is the power needed to run the circuit- always needed to recharge 1.5 cell- have gone back to 3.6v or 4.6v to power white leds with suitable current dropping resistor- lasts far longer. The pulsed power however meant you could run white led at 4x rating reliably for more light- however, only till cell charge dropped!.

originally I hope to put forward some words here, but after read your threads, I know YHou are all specialists, so that I dare not to say more again.

what I want to say, I hope to explain to Spark why people use such complex circuit instead of simple RC circuit to light the lamp?

The simple reason is when you use three cell to build your lighting led circuit, it cannt afford to long time lighting. when voltage down the led will be dark and then get out. as we all know the cell can be 1.6v to 1.1v. if you use simple rc circuit, you have to change r values time jto time to suit to light led, but when you use this circiuit the cell can change from 1.6 to 1.1v without affect lighting.

thats reason.

Hi all,

CN, how is the current limited? I don't see any means that stop the current rising to blow the diode, are you reliant on the internal Resistive component of the diode to limit the current within the narrow voltage band you're supplying?

Slightly off topic but of a similar nature is I need a constant current circuit to run from a supply between 10V to 28V, to give 100mA into a variable load of a few ohms (say 10) down to short circuit. The application is a simple cheap portable means to measure low resistance windings on generators. (3 to 100kVA). I achieve this currently (forgive the pun!) by the use of a series resistor which does not give me an accurate enough current to use directly and I have to start calculating to arrive at the resistance. This would give me a simple 10 to 1 ratio for the resiatance from the voltage.

I could buy a purpose made Kelvin meter but that would be expensive and would have to serve the 5 techs on the company. Murphy 's Law states that it will always be in the wrong techs van!

Has anyone any cute circuits up their sleeve?

Chas.

Hello capblanc

The Kelvin Double Bridge for measuring extremely low resistances, is a very worthwhile investment, and the results are always true, because of its basic nature.

With little to go wrong, you can be sure that your readings are quite accurate, and may also be used with AC input, if you need to.

These are far cheaper now, and better than they were some 50 years ago, when the instrument arrived in a varnished wooden box.

A simple pocket $10 pocket calculator on the job, assists with any calculations.

Kind Regards....

in spite of I vote you, its good for you to illustrate, but the bridge is always expensive.

Once the energy in industor is release, the current in the diode will stop.

its instant. the current of start into diode depends on the current of the transistor at shut time. because of current of industor cannt change suddenly.

2

] at collector of a transiftor will give you a constant current. its simple. its feature of transistor.

3

for a large generator, you cnant use a resistor of a current sampling. you'd rather use current sensor. there are lots of type for you to buy on the market

4

I could buy a purpose made Kelvin meter but that would be expensive and would have to serve the 5 techs on the company. Murphy 's Law states that it will always be in the wrong techs van!

I dont know your meaning. if you test temperature, you can use a multimeter. most of them can be for temp test.

Sorry CN, my problem is that we are a small service company and we need to measure these very low resistance only occasionally. Because of this it doesn't make economical sense to buy a kelvin bridge.

A simple constant current supply will do the job perfectly well, as I said I have managed so far with a simple resistor (actually a test lamp) but this is less than ideal and requires calculations which are easy enough but it is a problem when access to the work is difficult, which is often the case in the yachts.

Logically the best circuit would be one driving one amp through the circuit. this would give a direct reading on the volt meter scale (V=R). Very high precision is not requiered, 2% would be adequate.

I could probably "bread board" a system myself but I am sure there a folk out there who have a circuit already designed and probably a lot neater than mine and already proven. If anyone has a driver for 100mA or 1 amp i would be interested

regards

chas

oh, Kalvin bridge, I almost forget for loing time no use it.

speakstation is right at this spot.

now I know your idea is right to diy.

I cannt offer you such circuit at hands, but there are lots of themon the net for you to search.

if you hope to test a small resistor. I think you can also use a simple amplifier of IC like lm 358 etc. feedback resistor can selelct a precision resistor of 3k, 5.1k or 10k. and a voltage source add on the resitor you hope to test. measure the output voltage, you can deduce the resistance. very simple, you can get the precision value.

r = Vin/Vout * R

R precision resistor, r you will be mesured.