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

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32 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
50 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 ...
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1answer
25 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 ...
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20 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 ...
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1answer
39 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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35 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 ...
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0answers
61 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
46 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 ...
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1answer
34 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 ...
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2answers
41 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 ...
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2answers
163 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 ...
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1answer
41 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 ...
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2answers
73 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: ...
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1answer
182 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
89 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
116 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
27 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 ...
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1answer
165 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
307 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
76 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 ...
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2answers
681 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 ...
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1answer
92 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, ...
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2answers
52 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 ...
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0answers
101 views

Mini PCIe switch with 1 lane 2 devices?

I have a doubt, I have a SoC with 1 lane of PCIeV2 and I want to connect 2 wifi modules through PCIe to the SoC, so I want to use a PCIe switch to do it (the 802.11n is 600 Mbit/s and the PCIeV2 is ...
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1answer
212 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 ...
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1answer
233 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 ...
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2answers
118 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 ...
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1answer
120 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 ...
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1answer
80 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 ...
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0answers
43 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, ...
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2answers
1k 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 ...
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5answers
653 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 ...
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2answers
294 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 ...
2
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1answer
156 views

What must be rated maximum voltage of the boot-strap capacitor of a high-side MOSFET driver?

What is the maximum voltage that appears on a boot-strap capacitor? For example, in this circuit, does \$C_B\$ ever charge to a voltage level near \$600V \pm V_{cc}\$ ? Or does it charge to ...
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1answer
319 views

IC to interface between digital switches (12V) and microprocessors (3.3V)

I am working on an automotive general purpose ECU where I need to interface 12V digital inputs with a µC (3.3V). The PCB space is limited, so I am searching for a single IC as an interface between ...
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1answer
148 views

What kind of capacitor should I use in Buck topology if the load is a lead-acid battery?

I'm using BQ2031 to charge lead-acid batteries. BQ2031 takes battery voltage as feed back and controls the switching element according to it. Now the load is not a passive element, instead it is a ...
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3answers
4k views

What is the difference between 1N4001 and 1N4007 other than their maximum reverse voltage?

I compared 1N400x diodes here. As far as I see, all of their properties are same other than their maximum reverse voltages. Their maximum current recovery time reverse leakage current capacitance ...
2
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1answer
192 views

Micro switch that closes circuit twice, on press and on release

I need to implement a switch that closes a circuit twice for a short time - when pressed and then when released. The switch needs to be really small (should fit inside a 3.5mm TRRS headphone jack, ...
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5answers
295 views

Selecting a MOSFET for DC use

I have a general question regarding MOSFET Selection. I am trying to select a MOSFET for DC use. I am looking to replace a 5A 24V Relay with a N Type MOSFET. The MOSFET would be driven from a micro ...
3
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1answer
1k views

Selecting capacitor for voltage-divider of half-bridge high power SMPS

How to dimension the capacitor for the voltage-divider of a half-bridge high power (>5KW) SMPS power supply? The question is more on type of capacitor and current rating than the capacitance. I have ...
2
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2answers
189 views

What do I need to look out for when converting 9V example schematics to 12V?

What do I need to look out for when converting 9V example schematics to 12V? Most of my ICs work until 18V, and it seems to me all the resistor divider stuff is based on ratios, so it should scale ...
19
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5answers
673 views

How to ensure long-duration manufacturing of central components?

This question is related to project planning and minimizing risks in the future. Say that Company X builds this clever device (I do not own a company - I am just curious). The clever device takes ...
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2answers
227 views

Disadvantages of building own components (such as SR latch)?

So I browsed Digikey for way too long today looking for an SR latch. I wanted something low power that would use very low quiescent current for a varied range of VCC and work for between 2-5 volts ...
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2answers
399 views

Will the B constant for 10k ohm NTC thermistors be the same from all vendors?

I recently purchased a 10k ohm NTC thermistor from a local electronics store for which I couldn't find a datasheet. By going through the post How to measure temperature using a NTC thermistor I ...
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2answers
261 views

Varistor S10K30 for 24-40VDC input?

I was put in charge of redesigning a motor control circuit which accepts 24-40V DC on its input. As a side note: As far as i know, the existing circuit has been working fine for several years. The ...
0
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1answer
697 views

Will a capacitor of 10uf 250v work as good as a cap 10uf 50v?

what is the difference between electrolytic capacitors 10uf 250v and 10uf 50v? if i connect it to my circuit with a 9v battery? will the 250v cap work? or which is the most preferred for a 9v ...
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2answers
2k views

What is the “ammo” packaging method when ordering through hole parts?

I'm familiar with bulk, tape and reel, cut tape, and tube, but what is "AMMO?" Source: Fairchild 2N3904 datasheet, page 2
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4answers
274 views

Resistor selection for LED

This isn't asking the equation to determine the necessary resistor for LEDs, but more asking the general practice for selecting them. I've seen multiple circuits that have used much higher resistor ...
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2answers
406 views

Cannot find efficient current/voltage regulator to power LEDs

I have a 12V 4-pin common-anode RGB PWM'd signal being used to power some LED strips, and I would like to use it to power the VL-H01RGB00302 Vollong 3W RGB High Power LED - which is basically a set of ...
3
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4answers
1k views

Widely available IC for encording and Decoding DTMF data

I am planning to do some research in data transmission over the air. For this I am interested in DTMF encoding and decoding. Is there a widely available IC to achieve this? A circuit diagram using ...