- Joined Oct 26, 2011
He completely missed the point of the circuit; which was to allow LEDs to be gradually faded on and off sequentially via potentiometer R8, without having to use a bunch of comparators or opamps.Here's a circuit from "All About Circuits:" It has three technical faults; Can you spot them?
Firstly the Darlington transistor is not needed. It can be an ordinary transistor. And it doesn't have to be a "power" transistor. The circuit is taking a maximum of 25mA
Secondly, the 75R current limit resistor does not give very much tolerance for changes in supply voltage. A change of 1v will alter the current through the LEDs by 13mA. Most LEDs run on 15-25mA MAX and if the voltage drops by 1v, they will dim considerably.
And thirdly, the 470R resistors do NOTHING.
I also have another point of disagreement. Why use 18v to drive 6 LEDs. Since only about 11v is needed, you are wasting over 40% of the energy from the batteries.
You could drive 8 LEDs from a single battery as 4 LEDs in one string and 4 LEDs in a second string, and use less energy.
If you are going to design a circuit and add components such as the 470R resistors above, test the circuit to see if they have any effect.
This is one of the last things I do when designing a new circuit.
I gradually remove each component to see if it has any effect. Sometimes I have removed over 10 components that had little or no effect on the performance.
And sometimes a re-design results in 3 or 4 fewer components.
It's very embarrassing to find someone has omitted 10 components and the circuit works exactly the same.
Don't let this happen to you. Ask yourself, "What is each component doing?"
Either he doesn't know there are PCB versions of solderless breadboard, or he doesn't care. My vote is on the latter, he likes tearing other people down to build himself up. It is who/what he is.Here's a photo mistake. Can you spot the mistake?
The boy is soldering a "Solderless Breadboard!"
He originally claimed this circuit would not work, of course I test everything for the AAC book. So now it is over designed, I wonder if he ran the 3 month battery test like I did (it lasted past a month). Mine is verified over time and was overdriving the LEDs, not so sure of his, but then, his ego is not supported by his talent, so he has to tear the perceived competition down.Here is a circuit that is over-designed:
It can be simplified to this:
Before designing a circuit, look on the web and carry out research to see what has been done by other designers.
Apart from the first circuit producing a very weak output, it uses a lot of components. The second circuit produces a very bright flash and although it is not extremely efficient in current consumption, (the 47R is placed across the supply during the short flash-period), it will work on a supply down to 2v.
I never saw this attack on my FM transmitter.heres the article link...........
He must do that on purpose, since he NEVER posts the links back to where they came from, other than a base URL like "AAC". If he did post the link to the writeup that goes with the circuits, he would look like a fool. Instead, he creates his own writeup on what he thinks the circuit should do, as Wookie stated. It outright lies when you look at it in that context.He completely missed the point of the circuit; which was to allow LEDs to be gradually faded on and off sequentially via potentiometer R8, without having to use a bunch of comparators or opamps.
First one has to be able to comprehend what the intended purpose of the circuit is, before one can start re-engineering it. Had the suggested changes been implemented, it might work; but for something completely different than the original application.
So, Colin Mitchell gets awarded yet another engineering failure.
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