Questions tagged [3.3v]

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63 views

Where do current developments go regarding graphical displays for devices? [closed]

Our company is currently redesigning a piece of measurement equipment. We have looked at what display we have currently (It's a generic 240 by 64 pixel graphic LCD like this one ) and if there is any ...
2
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2answers
593 views

Best way to power a 3.3V circuit from 3.3V-to-5.0V source

I'm working on an add-on board that needs 3.3V power (~500mA) and should take power from its host board. The host can operate at 3.3V or 5V and I'd like to avoid using jumpers that would require the ...
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2answers
460 views

Can I use an Adafruit Trinket as a simple Android peripheral?

I want to control the standby state of an LCD panel through an android media PC. I'm thinking of using a Trinket as a cheap android USB peripheral. Is this possible? Or should I be looking at an FTDI ...
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0answers
1k views

RTC DS1307 3.3V I2C and Oscilloscope impedance

I'm working on a library for STM32 to learn I2C protocol (Software I2C, not hardware). I connect my DS1307 (Sparkfun BOB-12708) : (Here is the module schematic) : I remove welding on the SJ2 jumper ...
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3answers
907 views

Convert 3.3v to 14v?

I want to use a 4D Systems OLED display with an ATmega32u4 based PCB. I'm still working on designing the PCB and have hit a problem. In the data sheet it says that one of the power supply pins for the ...
2
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3answers
991 views

Triple output power supply

I need to power my device with three different voltages: 3.3V, 5V and 12V. I already have a 12V 1A power supply. So my questions are: Can I use the circuit below to get these three voltages? Is it ...
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3answers
17k views

MOSFET and 3 V power supply

I want to control an N-channel MOSFET from a 3 V power source. The thing is, I have difficulties understanding how to know the minimum Vgs value is to be applied for the MOSFET to be saturated. ...
2
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2answers
2k views

3.3V UART over 20cm ribbon cable inside an enclosure - EMC considerations

I am currently designing a device which internally consists of two circuit boards inside a fairly large, grounded metal enclosure. I'm designing one of the boards myself, the other is a bought part ...
2
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1answer
175 views

Unstable 96V DC to 3.3V Supply

So I've got a huge battery at 96VDC with a couple of electric motors hooked up to it that can draw huge amounts of current -- up to 600 amps. I need to power a few small electronics for a data ...
4
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4answers
5k views

Surface mount transformerless 230v to 3.3v on a small board

I am trying to design a 3.3V mains power supply to go on a PCB approximately 50x25mm in size (this will include other functions too!). I've come across the Supertex SR086, which is almost perfect, ...
2
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1answer
3k views

Interfacing PS/2 Keyboard to 3.3V inputs

I have had wonderful success with my new Mojo FPGA, so I decided to try something more difficult, interfacing with a PS/2 keyboard, but I cannot get it to work. Of course, I took the proper ...
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1answer
149 views

Microcontroller Evaluation board with SPI and 3.3V as logic high [closed]

Are there some microcontroller evaluation boards that support SPI, and use 3.3V logic? I am only familiar with the Arduino Uno, which uses 5 Volt logic. If such 3.3 Volt boards are available, which ...
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1answer
1k views

How to run Arduino-on-breadboard at 3.3V and still have USB communication to PC

I have built an Arduino on a breadboard (using an ATmega328PU) with an 5V FTDI USB controller. I want to be able to run the Arduino at 3.3V instead of 5V. It works completely at 5V supplied by the ...
2
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1answer
2k views

3.3v and many Leds: LED brightness?

I'm using a Teensy 3.0 which outputs 3.3v 100mA. I would like to connect many leds (probably 100…). Obviously I fear that the brightness of all the leds will be lower than I like to. I'm using the ...
3
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2answers
1k views

3V power rail from 5V

I've mistakenly ordered some 3V PIC18 L F14K22 instead of the 5V 18F14K22. 3V output is fine for the designed circuit but I need to make a 3V power rail from the available 5V rail. Since only a ...
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2answers
2k views

Drive a DC motor as the maximum speed with a Raspberry PI

I am new to the Raspberry PI and I don't have strong background in electricity (but I'm here to learn). The problem: I have a dc motor that works at 12V, and I'm trying to let it run with the raspi ...
1
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1answer
272 views

Different voltages with Ferrite Beads

I am checking the datasheet of one complex component, and the schematics of one demo board, and I find a difference that I would like to ask here. It is a 100Base-tx switch. The chip uses 3.3v for ...
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1answer
202 views

car Battery charger (3.3V)

I have a project in mind, but i'm stuck. I want to power a board (which works on 3.3V, 13/16 mah on reception and 37 mah on emission) with a battery from a car light adapter. It seems that standard ...
2
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1answer
3k views

Is this a practical minimalist 5 V-to-3.3 V circuit?

I've been whipping out quick-and-dirty USB-to-3.3 V supplies for XBee experiments. All it powers is the XBee (ser 1) and a couple of low intensity LEDs on the DIO lines, with a maximum total ...
5
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2answers
1k views

How should I alter my PISO shift register circuit so that it works with 3.3v instead of 5v?

I've followed this Arduino guide to build a circuit using a CD4021BE PISO shift register, and 10k pulldown resistors. It works perfectly fine with the Arduino's 5v supply. I then attempted to use ...
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2answers
2k views

5V Tolerance of 3.3V OUTPUT pin

Let's assume the following scenario: uC (@3.3V VDD) drives an I/O pin HIGH 3.3V (just to be clear, it's not an open-drain pin, so the p-channel mosfet of the output pin is actually driving the pin to ...
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2answers
609 views

How do I connect this 3.3V system and 6V ish system together?

I have an old 'Cybot' robot I built from a kit. I'm trying to mount a Raspberry Pi on it to act as brains. I'm a computer programmer, but my electronics knowledge is very limited. Have access to basic ...
1
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1answer
2k views

USB charging and powering circuit with MAX1555 and MAX1881

I'm new to (rechargeable) battery powered devices, but I found the following article about using the MAX1555 and MAX1881 for building a charging (via USB) and powering (µC-circuit, 3.3V, max. ~70mA) ...
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2answers
22k views

Converting universal AC to 3.3v DC @ 0.1A

There's a bunch of topics around this but i haven't found something that fits my requirements. I'd imagine this is a fairly common thing though so any pointers would be appreciated Basically i want ...
2
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0answers
2k views

Level shifting with BSS138 - weird values

I need to connect 5V and 3.3V devices via I2C as follows: I've connected 3.3V and 5V pull-ups and tried to measure the voltage. There is 5V on HV and TX_HV but 4,7V on LV / TX_LV. Putting TX to LOW ...
6
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4answers
14k views

Options for getting 3.3v @ 220mA from small batteries

I have a system running at 3.3v requiring 70mA at most times and 220mA at peaks (roughly 20% of the time). I'd like to find a way to power this from coin cell batteries or other small portable source. ...
7
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1answer
878 views

Open collectors & 74LVC245

I am trying to interface a PS/2 keyboard to a MSP430 for a toy. The PS/2 keyboard runs off 5V, but the MSP430 microcontroller runs off 3.3V. So I have a 74LVC245 level shifter to convert between the ...
0
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1answer
10k views

Programming 3.3v ATMega328 running at 16MHz [closed]

I know that running the 328 with 3.3v at 16MHz is "overclocking" it and slightly out of spec. Because of limited board space i'd like to do this though as all other components are 3.3v. I need the ...
6
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2answers
44k views

3.3v input to Arduino digital pin

Is it safe to bring a arduino digital input pin to high on a 3.3v input..from the 3.3v output of the arduino pin? Because, I need to reset a 3.3v device on one end..and get the arduino to know about ...
18
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5answers
19k views

What is a popular cheap and robust substitute for 2n7000 MOSFET for use with 3.3 Volt designs? [closed]

What are the popular equivalents to the 2n7000, for 3.3 Volt MCU circuits to switch higher voltage devices? Background: For 5 Volt microcontroller based prototypes and experiments, my go-to solution ...
4
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2answers
4k views

What must be the minimum input voltage of a series regulator?

I'm designing a series regulator. I need 3.3V in my circuit, the circuit has 5V and 9V available in it. What should be the minimum input DC voltage in a DC series regulator in general case? In this ...
0
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2answers
306 views

Automatic ranging level convertor?

I'm designing a PCB based on an ATxmega microcontroller (max. 3.6v tolerant). I plan to connect a range of external 3.3v devices. However, I do have a few 5v devices that I want to connect. There are ...
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3answers
2k views

I2C 5 <-> 3.3V Interface Chip

Does the classical 5V <--> 3.3V bidirectional MOSFET interfacing solution exist as a DIP package? Or is the commopn way to place discrete MOSFETs in your circuit? In that case, what are some common ...
7
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1answer
6k views

Voltage Level Shifting

I know there are similar questions on the site, but I wanted to ask it from a somewhat different perspective. I've got a 5V device (Device A) that can operate at 3.3V. I've got a 3.3V device (...
13
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1answer
4k views

How is this circuit for level converting (5V<>3.3V) working?

Does anybody know, how is this circuit exactly working? It is level converter between 5V and 3.3V logic and it is bi-directional. I have some theory, but I am not sure with it (I never worked with ...
7
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3answers
12k views

Bidirectional level swiching 5V <-> 3.3V

I am looking to interface a 3.3V device with a 5V one. This will require the shifting of the logic levels between the two devices. Doing this in one direction is a trivial matter, but I need to do ...
2
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2answers
865 views

Arduino or MSP430 Launchpad as a serial passthru to reprogram a Fonera router?

The Fonera has 3.3V TX/RX logic, I have a launchpad and an Arduino, can I use any of the cable/boards to reprogram or access the serial on a fonera? Fonera serial info is here: http://www.dd-wrt.com/...
9
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3answers
2k views

Best solution to get 3.3V from 5V-20V @ 250mA

For my Super OSD project, I need a +3.3V supply at 250mA from a variable input of 5.5V to 20V. Cost is a concern, as is size. Originally, I considered an LM317 in a SOT-223 package, due to the small ...
11
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4answers
9k views

Is it possible to drive TTL inputs from 3.3v microcontroller

I need a quick heads up on a problem I am trying to solve at work. I'm trying to connect to a parallel data port on an interface module we use to access smart cards. The port has an 8bit input and an ...

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