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Neil, Engineer
Category: Electrical
Satisfied Customers: 3777
Experience:  NZ Certificate in Engineering Electronics & Computing 25 years exp
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I'm building a custom DC power supply to replace the one my

Customer Question

I'm building a custom DC power supply to replace the one my rope lighting came from. The rope lighting takes fullwave rectified DC, which causes a strobe in the LEDs of the rope lighting. The exact rope light product is: Because I'm trying to save power, and because the lights don't have to be as bright as they are with the new capacitor-smoothed rectified, I'm trying to step it down to 41V. Ideally, I would have loved to step it down to 60V, but for now, this 41V one will do since i found it at a local Frys Electronics. The regulator is too different from the usual 78XX 3 pin package that I've been using for a decade. This one has 5 pins and the pins are labelled in ways I don't comprehend. It's a hybrid switching voltage regulator, and the exact part is NTE1840. I've been searching for examples on how to design a circuit using one of these switching voltage regulators and so far, i've come up with nothing that has been useful for me in regards ***** ***** part. While I continue researching the theory of switching power regulators. I'm wondering if there's anyone out there on JustAnswers who can tell me how to hook up each of those pins in a way that would result in 41V of DC, and a DC ground. it's possible I need to add additional components– capacitor, inductor coil, whatever. I would love any advice you can give me on how to get this up and running. It would be receiving the smoothed fullwave, so there's a minor ripple. For convenience, the PDF for this switching power regulator is here:
Submitted: 2 years ago.
Category: Electrical
Expert:  Russell H. replied 2 years ago.
Hi, thank you for contacting My name is Russell. I will do my best to provide the right answer to your question.
Actually, I think you might do well to abandon the NTE regulator, if you cannot afford capacitors and you don't comprehend it. (It's true, we all need to learn something... but still, if it's too hard to bother with now, it probably always will be.)
But anyway: my idea is, that you use a simple zener diode voltage regulator - if they have one in the 40 V range, which I am not sure of.
Zener diode voltage regulation is approximate and primitive - but simple. Good enough for a string of LEDs with no filter capacitors.
Checking on that idea - I find that a 40.0 or 41.0 V Zener diode would be very hard to find, if one exists at all.
I cannot - upon making an effort - find any indicative information about how the NTE1840 is supposed to be hooked up in a 'typical' circuit. Thus for me, also, the pinouts and their odd names remain a mystery, I confess.
At least, this seems to be to indicate that something simpler - for such a simple application - would be preferable.
Perhaps 4 x 10.0V Zener diodes in series might provide the crude 40 V regulation you seek? But anyway, something simpler and more obvious than the NTE1840 would be preferable! (One reference says that chip is mostly used in TVs. A rather more elaborated context than yours.)
Expert:  Neil replied 2 years ago.
I am pretty certain the NTE1840 is a fixed voltage regulator used in TVs....
The data sheet confirms this "Output Voltage is Pre–Fixed – No External Adjustment is Required"
So the reason there are no application circuits is that none are required...
The Output voltage spec is a little weird on the spec sheet you gave but more detailed investigation confirmed this is a 41.5 volt rated output...
So what are you looking to feed this chip with? 41v AC or DC?