Questions tagged [lm78xx]
LM78xx are a popular series of linear voltage regulators. To name a few 7805, 7809, 7810
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LM338T Output to 5V issue with LM1085-IT 3.3V
I am using 12V , 2A DC power supply as an input to LM338T and LM1085-IT 3.3 , for 5V and 3.3V output respectively.
The issue i am facing here is when these both voltage regulators are connected in ...
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Does the output bypass capacitor of an LM7805 double as a decoupling capacitor?
I'm using a 5v linear regulator (specifically an LM7805) that outputs directly to an ATMEGA328P. According to the LM7805 datasheet (page 23) input and output bypass capacitors should be used, as seen ...
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LM7812 and decoupling capacitor value
LM7812 voltage regulator is recommended to be used with decoupling capacitors at its input and output as in the below diagram:
And here is the part from the manufacturer Fairchild(see recommended C1 ...
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Crude LM7809 9V NiMH charger
I want to charge my 9V NiMH cell with a LM7809. The problem is that I want to limit the current output to 20mA or 30mA. How can I limit the current output from that voltage regulator with simple ...
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LM78xx Reverse Polarity and Reverse Bias
I'm building a circuit that will use a LM7805 and LM7812 to produce 5VDC and 12VDC respectively, with the input power being ~16VDC from an external wall wart.
I already fried one of each regulator ...
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What does the CT suffix stand for in voltage regulator?
Given a regulator such as the LM7812, what does the CT suffix stand for in a voltage regulator in Fairchild LM7812CT)?
I've googled and went through the related datasheets, but could not find the ...
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Do 74HCxx chips require a linear voltage generator?
Recently I've read a book that says it's absolutely necessary to use a linear voltage regulator like LM7805 in circuits that use any of 74HCxx chips (CMOS logical gates). I thought that this advice is ...
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LM7805CV output voltage drop to 2.5v after connecting load
I've made a simple linear power supply for micro-controller with a transformer and LM7805CV as seen in the picture.
LM7805CV input voltage is 35V and output without load is 5V but after connecting a ...
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Jumper out an LM7805
I have a 5V hobby circuit that will be externally powered from a wall wart, with way less than 1 amp. For full flexibility, I'm thinking of using a simple LM7805 regulator - but that has a 7V minimum. ...
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buck converter and regulator
First:
I want to use DC DC Stop Down Buck Converter, im using this one:
- https://www.aliexpress.com/item/10pcs-24V-12V-to-5V-3-3V-3V-DC-DC-1A-Step-Down-Converter-Voltage-Regulator/32671102728.html
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Why 7805 regulator gives output 6 volt?
I am using 7805 and 7815 for the voltage 5 V and 15 V respectively. I provide 24 V to 7815 it is giveinng me output voltage 18.5 V instead of 15 V. According to 18.5 V to input to 7805, its output is ...
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Running Regulator Under Voltage
Is there any disadvantage to running a Linear Regulator under the minimum voltage stated in the datasheet? For instance, In the datasheet of the LM7812C2T, it says the minimuim voltage in order to to ...
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Decoding power supply regulation (42V from 5V)
I am referring below schematic where 42V is generated from LM78L05 regulator IC. But I am not able to get how LM78L05 can generate 42V? Which concept is used to get such high voltage from 5V regulator ...
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Solar cells with 5v regulator: would it supply more current than available?
I recently bought online three solar panels rated 6v x 500 mA for some circuits I had in mind. What I got instead were 12v cells, and I am certain they are rated 250mA, since the seller had those too.
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AC supply to digital output
I need to sample 8 power switches connected to 230 Volt supply. I want to record the status of these switch every 10 seconds and send to cloud for which I am using arduino with ethernet shield.
For ...
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xV input from a wall wart to +9v, -9v, +9v output
I am trying to modify a circuit Circuit schematic that requires three 9v batteries. Two to supply +9v/-9v for an lm358N opamp, the other +9v is to drive a DMM display.
I have dozens of wall warts of ...
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Switch Mode Alternative to LM7805/LM7905
I am attempting to design a dual rail power supply PCB for a university project. There are a number of restrictions - namely that it maintains > 80% efficiency regardless of the current draw. I was ...
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Question regarding the LM7810 voltage regulator [duplicate]
Is there a simple way I can hook up this regulator to reduce the maximum output current from the 1A rating down to a 500mA maximum output without affecting the 10vdc output?
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Making LM78xx fail safe against short, open, reverese bias, flyback, etc
I want to use LM78xx for various applications. What I am concerned about is its failure modes.
1. Failure to Short
Not shorting Vcc to ground!! I mean shorting V_input to V_output.
Assume that you ...
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How to select proper capacitors and capacitance for LM78xx voltage regulators?
I want to use LM78xx voltage regulators for various projects. I want to know in general, how should I choose a correct value for input and output capacitors of LM78xx family when I want to change DC ...
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LM7915 delivering more than -15v
I'm trying to build a regulated power adapter using LM7915.
Before everything, I built on a protoboard the schema included on the datasheet (from ST). But, instead -15v, the output is -19v...
I'm ...
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78L05 questions [duplicate]
What are the capacitors on the input and output of a 78L05 for?
I saw a lot of different schematics with a lot of different input and output capacitor values.
So now I am really confused, and I'm ...
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48V DC Power Supply Using LM7812 in Series
I want to create a 600W 48 VDC power supply with input taken from the line (220VAC) and so far the steps that I've had in my mind are:
Stepping-down the voltage to 15V using transformer with 3A ...
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7809 Linear Voltage Regulator Outputs in Series
I'm building a linear power supply that converts 120VAC mains voltage into multiple 9VDC, isolated outputs. I'm using this transformer that has the proper primary winding and 8 secondaries that I'll ...
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Can a 5V regulator connect directly to a voltage divider to obtain a 2V output?
In my circuit, a lm78l05 is used to provide +5V voltage to other parts. And now I need another +2V source to shift my input signal from +-2V to 0~4V as the ADC ad7682 limits the input signal range ...
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Can I obtain a new voltage source from outputs of two cascaded linear voltage regulators in practice?
I have a device which works with 7V. I have a 7812 and 7805 already running in the circuit. Can I use the outputs of this voltage regulators to feed the 7V device?
I know this is possible in theory. ...
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Is a full-wave rectifier really required with a 7810 regulator?
I'm possessed of a 12-0-12 500mA transformer.
To supply a stable 10V, I seek to connect a bridge rectifier, roughly filtered with a 1000uF/50V electrolytic capacitor and a 7810.
Is a bridge, or ...
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