Help understanding a simple circuit..

July 24, 2017, 12:48 pm

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I found and downloaded a schematic online a while ago, now I can't for the life of me find the source again so I have no description of its operation.

Can anyone tell me the function of the inductor and snubber here please? Is it there to smooth the pwm across the load or just arrest voltage spikes? Also Q1??, it doesn't seem to match any n or P mosfet symbol I've seen, at best its a mixture of both.

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Design Request - Deceleration Activated Brake Lights

July 24, 2017, 12:54 pm

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Commercial motorcycle accessories called "smart brakes" activate the brake lights whenever the vehicle starts to decelerate. This starts the brake lights a second or two faster, upon engine braking (which is strong for motorcycles) as soon as the rider rolls off the throttle. The faster brake lights are a real safety enhancement, and also allow for lighting the brake lights if the rider simply uses engine braking, without touching the regular brakes.

Commerical devices include...

Design Request - Deceleration Activated Brake Lights

Designing of cascaded PID

July 24, 2017, 1:44 pm

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I'm doing PID temperature controller using PLC.

I'm doing a cascaded P, and PI controller of both temperature set points.

My question is how would I map the output of the first controller which is PI which should be converted as a temperature set point of the the second controller ?

Switching circuit

July 24, 2017, 3:00 pm

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Hello, I am playing around with propulsion like the resonant cavity thruster. I don't know anything about electronics, very deeply, and I only hope that something safe and dependable can be made using a 240 Watt DC adapter or drawing in 1.2 kW from a household circuit, without injury or the possibility for disaster, if it is made with sound principles and to be as reliable as any household electronic device.

The idea is to make an AC alternation across a wire antenna, with the current going...

Switching circuit

Generating a frequency or multiple frequencies with a Microcontroller's output pins

July 24, 2017, 3:29 pm

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I am a newb and just started to learn programming with Microcontrollers. I don't know whether I should use BINARY or C Programming on MPLAB. I want to generate frequencies between 1Hz to 1Mhz on the pin outputs of a Microcontroller. The frequency has to be very accurate and I want to use a quartz crystal along with the frequencies so they may be highly accurate.

An example I would like to accomplish.

- A microcontroller having 1 output pin as 10Hz
- A microcontroller having 3 output pins...

Generating a frequency or multiple frequencies with a Microcontroller's output pins

Introduction to myself and my workshop

July 24, 2017, 3:36 pm

≫ Next: Identify parts in a circuit diagram?

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Dear friends. Allow me to start warning you that same as I love to read threads were things are explained in detail, my own style is very lengthy. As I have serious trouble with my health, reports I do write in threads also have the purpose to bring me up to speed when I have interrupted my activities around any certain topics.

I have been since early in my life a fan of science fiction and so my goal was to study space and aeronautical engineering in Germany. I only pursued this study for...

Introduction to myself and my workshop

Identify parts in a circuit diagram?

July 24, 2017, 5:23 pm

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How do I identify parts in a circuit diagram?

E.g. this one?

https://www.scribd.com/doc/207782153/Dell-2407-WFP-Power-Supply-Rev-A11-Schematic-Diagram

What is e.g. Q653? It is a SMD transistor of some sort just from the look of it, but what kind? I need to know exactly.

Is this circuit diagram simply missing some mapping between local identifiers used in the circuit diagram and what those parts correspond to, or am I supposed to be able to figure it out some other way?

LM2917 Tachometer for V12

July 25, 2017, 6:38 am

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Hi folks, hope someone can help me. The rev counter on my 1973 Daimler V12 has given up the ghost and the chip (I'm assuming that is the fault) is unidentifiable - the numbers on it are MIC 7303 (Smiths instrument). Does anyone know anything about this?

I have now decided to try to make my own. First I tried using a 555 monostable but the signal from the coil is too erratic and I found it difficult getting the needle steady. Now I'm trying with a LM2917 using the circuit below (taken...

LM2917 Tachometer for V12

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Standby Circuit - Your opinion is needed

July 25, 2017, 8:13 am

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Hi

i need some guidelines for the repairing of an old home theater...
probably some of you will say "why i bother and i don't get a new one"...

well...it's not mine and i'm not fan of such devices but if i manage to repair it
i will make a friend happy

To the point...the home theater model is Philips HTS3164, the VFD is not
working nor the power led..neither there is any video output, thus looks
like a dead unit.

searching around the power supply seems it works and every voltage is...

Standby Circuit - Your opinion is needed

Pick and Place Machine for sale UK, ST7

July 25, 2017, 8:24 am

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Selling my MDC Luna EXP SMT Pick & Place machine. Full details here..
http://www.ebay.co.uk/itm/152622704698

Voltage tripler with PWM signals

July 25, 2017, 9:47 am

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Hi there, I'm having a problem tripling the voltage of a PWM signal, I need to convert 3.3 in at least 9.9V but I'm having a tough time in simulating that in LTSPICE, I can only get it to work for a SINE wave signal and even then the voltage doesn't even reach 9.9V but rather about 8.5V.
What am I doing wrong and is there a way to make this work for Pulse signal?
I'll attach the image of the circuit and result.
Thank you

EDIT: I've realized the voltage wasn't reaching the 9V because I was...

Voltage tripler with PWM signals

Driving 10 5050 RGB LEDS

July 25, 2017, 11:34 am

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Hi all,

I am trying to build a circuit to drive 10 5050 RGB LEDs (https://www.sparkfun.com/products/10866) . My circuit is powered by 3 x AAA batteries (4.5V) and the microcontroller is 3.3V. I am using a voltage regulator to step down from 4.5V to 3.3V.

I need to turn on all 10 LEDs at the same time, with the same color. The MCU can control what color to display, eg. red, green, blue, red+green, red+blue and green+blue. I also need the LEDs to be as bright as possible. I will...

Driving 10 5050 RGB LEDS

Reflective vs Direct Optical Sensing (Part II)

July 25, 2017, 11:51 am

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A follow on to an old discussion here. I have two separate working circuits - one for reflective sensing indoors and another direct sensing (using sunlight) outdoors. I would like to have one circuit which varies resistance based on the amount of light present. For now, I'm trying to accomplish this manually changing resistor values but can't get enough variability using either of the...

Reflective vs Direct Optical Sensing (Part II)

Baseband processing and Digital to Analog Conversion

July 25, 2017, 1:00 pm

≫ Next: Need component options to Start/Stop Pump 24VDC 15A

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Hi Guys,
I have a question on the need for Digital to analog converters in Transmitters. To elaborate bit further:
1) Because of the advantages of the Digital signals, most go the signal processing in wireless communications is performed in baseband. But my question is: Since digital modulation is also a part of baseband processing, how can we still say its baseband as a carrier signal (which has high centre frequency) is used for modulation?
and
2)...

Baseband processing and Digital to Analog Conversion

Need component options to Start/Stop Pump 24VDC 15A

July 25, 2017, 1:31 pm

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Subject almost says it all. I'm looking for component options to start/stop a pump that runs on 24VDC and draws 15A. The 15A being the key (problem). Electromechanical relay and solid state relay I already know about (though I haven't found one to switch that much current yet).

What are my options?

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Funny Images Thread!

July 25, 2017, 3:19 pm

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Post Images which seems to be funny to you.

QM1323 Multi meter -What is the red light built in used for ?

July 25, 2017, 3:44 pm

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I have one of these QM1323 MMś and the red lamp flashes with no apparently consistent reason. Does anyone know what its for ?


Cat III Multimeter with Temperature


• Data hold
• Relative measurement
• Case included

A budget-priced meter with everything you need - capacitance, temperature and 10A on AC and DC, compact and light weight with rugged moulded case.

Specifications

Category: Cat III 600V
Display: 4000 count
Basic accuracy: 1%
DC voltage: 600V
AC voltage:...

QM1323 Multi meter -What is the red light built in used for ?

Look at the schematic...

July 25, 2017, 4:53 pm

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What's the use of 5th diode in this schematic..(which is in parallel with cap)?
I think this is a circuit to drive led from mains AC.

Sorry if this question is too simple or obvious.. I just want to know what that diode's doing there.

philips crt TV screen going off after power ON

July 25, 2017, 7:06 pm

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my philips crt tv screen going off when power on. it will remain only about 4 seconds and suddenly going off.. but power supply remain on position.. plz help me.. thank you

Identifying circuit board part

July 25, 2017, 7:08 pm

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Trying to repair a board for an irrigation controller. This part has no id i can see. It is cylindrical, silver 5.8mm x 1.7mm dia., pin type. The board has Y2 . Anyway to id from this info. May be a crystal or oscillator. Thanks