All related to methods to select the correct components and/or component values to specific applications

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15 views

Carry Select Adder

![ we used k-bit adders to design an Nbit carry select adder. However, we can use variable-length adders instead of fixed-length adders. The following shows the specification of logic blocks we are ...
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1answer
50 views

chosing the right Hall effect sensor

For a student project, I need a Hall Effect current sensor. What I am going to do is to charge 8 rechargeable Li-Ion batteries of 3.7 volts in series with 34 volt supply and the buck circuit frequency ...
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1answer
59 views

Why is this a bad MOSFET/Driver for a Tesla Coil, what does one look for in a good one?

MOSFET: http://ixdev.ixys.com/DataSheet/99175.pdf Driver: http://www.irf.com/product-info/datasheets/data/ir2183.pdf What factors should one consider in selecting a good MOSFET/Driver combo, and ...
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4answers
89 views

Practical Considerations of a Butterworth Filter

I'm trying to design/implement a low-pass filter for the amateur 2M band (144-148 MHz). To meet FCC regs, I need harmonics to be at least 40dB down, so I calculated a 7-stage Butterworth Filter with ...
2
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2answers
41 views

Components with multiple possible values - how to designate on schematic?

Quite often it happens to me that values of resistors or capacitors don't play such a significant role. This is mainly the case with decoupling capacitors and e.g. LED series resistors. Often in ...
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38 views

What parameters are key in selecting a transformer to pass digital data?

Looking to fiddle around with some digital signaling through transformers. Never done, so this is just to experiment and see what it looks like. For the purpose of digital isolation, what types of ...
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1answer
44 views

How do I select transistors for logarithmic amplifier?

I need a logarithmic amplifier and found this equivalent schematic in the datasheet for the LOG104: The LOG104 is rather expensive, so I want to build this myself. What are the requirements for the ...
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37 views

How does one change only the frequency of an alternating current? [duplicate]

Suppose standard voltage, current, and frequency AC power is readily available for a project that requires the available standard voltage and current, but also requires an arbitrary number of cycles ...
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24 views

Advantages of integrated level translator

I've been trying to decide on what level shifter approach to use for a single, bi-directional, slow signal going from 5V to 3.3V. My input could be a switch to 5V, or maybe a logic level output. ...
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0answers
22 views

Solenoid Valves for Air Control

I'm working on a project that involves inflating and deflating (possibly even applying vacuum to) a large number of isolated chambers. I'm fairly certain this job can be done using a microcontroller ...
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0answers
55 views

RFID tech for PCB identification?

I am looking to use a soldered on RFID "thing" for board ID. The requirements are: a) Cheap b) No power supply needed c) Hand held reader/writer d) In place programming after PCB manufacture Any ...
2
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2answers
197 views

LED capable of either IR or visible light (not at the same time) [closed]

I'm looking for a type of LED (or some other small light emitter) with two modes: IR light only Visible light, if it also emits IR light here it doesn't really matter Could something like an "RGB ...
1
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1answer
52 views

Which MOSFET is best for me? [closed]

I plan on driving a heating coil of about 1.4 Ohms from a 3-4V power source; which gives an current draw of 2.14-2.85 A. So Watts from the following info is 6.42-11.4 W of power. The MCU will output a ...
0
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3answers
107 views

LED Resistor Choice with changing voltage

I'm planning on adding leds to a small quadcopter which runs on a 1s lipo battery. I am planning on attaching the leds straight to the battery rather than the regulated voltage the main circuit board ...
0
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1answer
48 views

Short 2 wires when a third is powered

I'm using an Arduino for a home project. Say I have 2 wires, connected to a breadboard in different columns (not shorted). When one of my digital outputs on the Arduino is HIGH, I'd like to short ...
2
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1answer
109 views

A circuit/component which can reduce own resistance with increase of current

I'm trying to build following circuit for single-phase 230VAC grid: 0---(LOAD)---(MY_DC_CIRCUIT)---Phase MY_DC_CIRCUIT doesn't have its own power source. The power is considered to be taken from the ...
2
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2answers
263 views

How can I tell if a given MOSFET can be fully driven by 5V TTL high signal? (what should I look for on the datasheet?)

How can I tell (by reading the datasheet) if a specific MOSFET can be turned fully on (with the minimum drop) with simply 5V on the gate? (assuming 5V or 12V potential between the drain and source). ...
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3answers
254 views

How to find out if a microprocessor is powerful enough

Everybody knows its easy to develop a proof of concept for an embedded device on a rasbperry pi or even a PC, although when it comes down to choosing a microprocessor for your product, it is difficult ...
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0answers
90 views

Finding an equivalent of BS108 and NDP6020 transistors

I want to implement the below circuit for automatic power off of a microcontroller that will be battery powered: I took this from the following forum: ...
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2answers
193 views

MCP602 alternative?

What can I substitute in place of the MCP602 in the following circuit? It is a pulse rate detector.MCP601/2/3/4 are not available where I live. I have attached the relevant instructable and the MCP602 ...
0
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1answer
45 views

How to change component values when changing tube B+ voltage

I'm starting a build a tube headphone amp from diyaudioprojects.com (the simple one: http://diyaudioprojects.com/Solid/12AU7-IRF510-LM317-Headamp/) The projects uses a 12V supply for the tube plate ...
0
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0answers
25 views

Recommended components for OKR-T/1.5-W12-C typical circuit

The datasheet for the Murata OKR-T/1.5-W12-C, http://power.murata.com/data/power/okr-t1-5-w12.pdf, doesn't show any suggested values for RP and Q1. What would be the suggested value of the resistor ...
0
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1answer
45 views

TPS54383 switching regulator components.

I'm trying to build a switching regulator using the TPS54383 dual output regulator, Now I've got most of the components and schematic figured out here. pdf Except the inductor's and diode; I'm ...
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0answers
61 views

Good narrow beam, modulated IR sensor suggestions

I am looking for a narrow beam, modulated, digital IR sensor that can detect a distance of at least 10 cm (longer is better). I've talked to mouser and pololu and they were unable to leave me in the ...
0
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0answers
70 views

Bi-color LED for low and high-inpedence switching

I designed a circuit to make glow a green LED when a input pin is in high impedance state. When the input pin is connected to ground, Red LED must glow. I've been searching for a bi-color LED for this ...
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1answer
49 views

Are there any single logic gates which are just individual components?

As the question says, I need a NOT gate for a simple Bi-Colour LED circuit. I do not want to use an IC with 6 or 7 integrated as I am only going to use 1, so it's just a waste. So, do individual ...
0
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1answer
37 views

Size of passives for active filter

I am working with the CS42436 codec, and in their datasheet, they have recommended values for components to be used in an active filter that takes the differential outputs from the DACs and converts ...
0
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2answers
55 views

Component selections for the ETA3406 DC/DC converter

I was browsing Seeed Studio's Open Parts Library and found the ETA3406, which is a 1.5 MHz 1.2 A Step-Down Converter. It's pretty cheap, and looks very useful for something I want to build, but the ...
4
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2answers
237 views

Inductor selection for obtaining a noiseless analog power rail

I interface an image sensor, and the design schematic for power supply is: How do I choose one from the available 3uH inductors based on the specs? I figured the maximum current and dc resistance ...
1
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1answer
63 views

Selecting continuous pull type solenoid

I own a Rail track master and it needs two pull type continuous solenoids. The age of this machine is from the 1950's and both of the previous solenoids were unidentifiable. These solenoids operate ...
0
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2answers
148 views

What are the selection parameters for an NPN BJT?

I'm building an NPN-based driver circuit for disconnecting my battery level measuring voltage divider when not in use. Here's the circuit: ...
8
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1answer
204 views

Antenna matching network topology

In tuning an antenna, there are multiple possible topologies that will take it to the middle of the smith chart. Some differences that I can see between them are: Component ESR (losses). Effect ...
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3answers
142 views

Finding a replacement voltage regulator… what do the codes mean?

So I need to replace the following voltage regulator in an old Atari as it's registering 0.5V between output and ground and 24V on the input, but it's supposed to be providing 12V on the output side ...
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2answers
186 views

How do you choose a diode for a 5v to 3.3v clamping circuit

I have a logic input that is 3.3v and I want to be able to allow it to interface with either 3.3v or 5v input signals w/o worrying about it being damaged. I would like to use a resistor with a ...
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0answers
30 views

Can I change a design from using one polypropylene cap to four PEN/PET caps in series?

I've inherited a design for a SEPIC converter that uses a polypropylene input filter capacitor from CDE. (Specific part number 715P472516LD3.) I'm considering shifting this design to surface-mount ...
2
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1answer
214 views

Choosing capacitors for Microwave RF application

I've recently been given a project to lay out some PCBs which will contain a few Mini-Circuits RF amplifiers, and their associated biasing components. However, since I need to have several stages of ...
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5answers
435 views

Which parameters in datasheet give information about a BJT's step response quality?

I did a test with randomly chosen 12 NPN BJTs. I applied a clock pulse to each of them and observed their collector voltages. Some of them showed very low rise time, while some responded terribly ...
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0answers
88 views

Best possible specs for a MEMS mic in 2014?

I want to use the best MEMS mic that's on the market today (June 2014) in terms of audio quality. Since I know that "shopping" questions are forbidden, I'll phrase it like this: What are considered ...
4
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3answers
743 views

How to tell if an electronic component is counterfeit?

I've been looking into sites (like Alibaba, etc...) for components, but they are usually at the price of the rain. How can someone know if a company or factory is not a scam and that those components ...
1
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1answer
137 views

How to find SMT equivalents of TH parts?

A lot of times hobbyist circuits are designed with thru-hole components since they're easier to solder. What approach do you take when attempting to find the SMT equivalent of a TH part? For example, ...
0
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2answers
63 views

Does DC-powered polarizing film exist?

Does anyone know if there is a component or a solution for creating a switchable polarizing film using DC-power? (i.e. a film/glass/substrate/etc that can be switched between a polarizing and a ...
0
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1answer
335 views

Finding/figuring out pin configuration on undocumented components

I recently purchased an assorted set of LCD/LED displays, and inside there were a set of components which I cannot find a datasheet for upon googling the component number. For instance in the ...
7
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1answer
240 views

Help me modernize this audio circuit

When I was a kid, I built this circuit. You hook up a small capacitor to the test leads or maybe a couple in parallel and the speaker will output a different pitch based on the test capacitance. I ...
1
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2answers
138 views

How can I maintain a fix voltage until my battery is almost dead?

I am experimenting with a simple circuit. I have an Arduino board, a proto-board and an IR sensor (that uses electricity from the Arduino board). I use a 9V battery to feed the Arduino. My problem ...
1
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1answer
130 views

Rectifier component for PCB

I'm looking to change my breadboard design of an amplifier into a PCB. This is the first PCB I've designed and I'm not sure what sort of components to get. My original full wave rectifier is made ...
1
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1answer
93 views

How do I find a matching plug & header pair?

I'm browsing board to wire type connectors. My aim is to solder a header on my PCB, and use a plug to receive/transmit signals from it. As far as I see, the headers and plugs are sold separately, and ...
0
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0answers
44 views

How to chose a compatible, drop-in replacement for a TSOPII-54 SDRAM module with more space?

I have a device that uses a PSC (Powerchip) A2V64S40CTP-G7 TSOPII-54 SDRAM chip. It's a 64MBit (8MB) RAM module. I'd like to put a larger chip in that device, and what I need to wrap my head around, ...
5
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2answers
2k views

How to Calculate Complex Low Pass Passive RLC Filters?

I have designed a FPGA based DDS and now I want to add a low pass filter to its output. Previously I was working on a project based on AD9850 DDS(0-50MHz) and I had a commercial module for it that had ...
9
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5answers
869 views

Sensor for ultralow (to -85°C) freezer monitor

I am planning to build a series of Arduino-controlled temperature-reporting units for a room full of "Ultracold" -80°C freezers. (I ultimately want to convert the signal to a serial stream that will ...
2
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2answers
406 views

Component for covering a very tiny hole (pinhole camera aperture)

I am experimenting with a pinhole camera - it is basically a camera with a very small hole (only 0,2 mm in diameter) instead of a lens (Wikipedia) I am trying to design the shutter - something that I ...