frequency filter

I've never designed a filter before and I'm not sure if you can do this. Basically I need a way of filtering out all signal except for signal in the range of 40-150 Hz

Topic by guyfrom7up 10 years ago  |  last reply 10 years ago

High frequency generator

I want to build a VHF (high frequency) powerfull generator for make an unusual form of lightning. It must produce microwaves 10 - 20 mm. length. Please, write here if you have any information about such generator.

Topic by 012345678910 9 years ago  |  last reply 9 years ago

Arduino High Frequency?

I have an Arduino Duemilanove and was wanting to know how and/or what I need to do to create a high frequency signal. I dont have a set frequency in mind but would rather know how to change it so I can gradually step it up until I get desired results.....Have looked at a lot of stuff on google for how to do this and most refer to a wiring.c file but mine appears to be an updated version to what they have...Anyways any help would be greatly appreciated =)?

Question by afreeland 8 years ago  |  last reply 8 years ago

Variable frequency generator? Answered

I'm looking for a way to build a simple frequency generator that generates high and low frequencies. I was thinking of using a POT to control the frequency range. I looked for it all around but the search didn't help much.

Question by Misac-kun 6 years ago  |  last reply 6 years ago

Radio Frequency Generator? Answered

Hi I am doing a project and it requires a radio (or anything longer than human eyesight) frequency generator. Is there any easy way i can do this, with parts from home or radioshack?

Question by LiquidLightning 8 years ago  |  last reply 8 years ago

Frequency help needed.

Does anyone know what frequencies of laser light can effectively and efficiently ionize normal air into conductive plasma?

Topic by Masterdude 9 years ago  |  last reply 9 years ago

Low frequency amp? Answered

For a future project (blue barrel infra sub woofer with ducted fan) I'm already looking for parts. I see most amplifiers and amp chips (like the TDA7294) have a frequency response usually 20 - 20,000 Hz. But I'm interested in a range from 0- ca 40 Hz. As far as I understand, the low cutoff is to protect the driver (speaker). Would it be possible to circumvent the low cutoff, or would I have to build from scratch? (I'm thinking in a 70 - 150 W RMS range).

Question by BobS 9 years ago  |  last reply 9 years ago

Variable frequency drive

Hello there instructables, I have another question discussing maglev theory and i was directed that the true way to build this project was to use 3-phase power! So this question, although related, is also an entirely new project in its own right! Now to the point, i have been researching single to 3-phase conversion, and there are a few options available like rotary or static phase converters, but i have been intruiged by a device called a variable frequency drive! Okay so what i understand so far (i think) is that these convert ac to dc, run that dc through a H bridge rectifier using igbt's and then convert the 3 outputs back to ac...... okay assuming my analogy is correct so far, to my question, 1. How are the igbt's triggered in the h bridge? do they use a function generator with altering timesteps to create the seperate phases? 2. Also how are these kept in sequence with eachother? Many thanks in advance for any help you can provide!

Topic by Xmortx114145 6 years ago  |  last reply 6 years ago

High Frequency Alternators

Look at a picture of some arcs from a common spark-gap Tesla Coil, and then compare it to the arcs from a solid-state. What makes the two so different? The difference comes from the Solid-State Tesla Coil to operate in CW (constant wave) mode. This means that its power supply is uninterrupted, whereas in a spark-gap type, power is being switched on and off hundreds of times per second. If the output terminal of a CW coil doesn't have a brake out point, no corona or spark will occur. For anyone who's investigating wireless power transmission or Tesla's version of radio, this is a very helpful feature, since corona only wastes energy. And if it does have a brake out point, it can create some pretty interesting spark displays, as I mentioned above. An arc to a grounded object increases the current in the arc to such a point that it turns into a white-hot "flaming" discharge. All-in-all, a CW type coil is a pretty interesting kind to observe. But solid-states can be pretty difficult and annoying to build, and expensive as well. Since solid-state technology obviously was not available to Tesla, he found a different way to operate his coils in CW mode- a generator that was specially designed to produce radio-frequency power. He had originally created it for high-frequency arc lighting. Today, I have seen absolutely no coils run by a high frequency alternator. Of course, an alternator would be admittedly difficult to build, but since it could probably deliver more power than a solid-state coil, it would be worth it. Does anyone know if there are any companies that still make these alternators? Would anyone be interested in recreating it? Should we even bother? Thank you for listening. Peace!

Topic by ElectricUmbrella 9 years ago  |  last reply 4 years ago

Frequency of 12v halogen transfomer?

Hello everyone.. I would try using a 12v transformer halogen (please see photo) for flyback driver (about 10-30 watts) .But seller sell on Ebay do not know the frequency of 12 vac, so could you help me to know that(frequency of 12 vac out) thank you in advance.

Question by lam 4 years ago  |  last reply 4 years ago

Can I reduce the frequency of the newsletter ?

Hello all fellow makers ! It seems I can change the frequency of almost any other email sent from Instructables but I can't figure a way to reduce the frequency of the newsletter.  Once a week would be nice.  Is there a way ? Thanks, Guillaume

Topic by aka.guf 4 years ago  |  last reply 3 years ago

Frequency driven speed for chase lights..?

I have some battery operated chase lights (Christmas lights) that I want to wrap around a musical instrument.. When I play a note, I want the frequency of the note to drive the chase light speed. So higher notes will make them chase faster than lower notes.. How can I do this?

Topic by 3DPiper 5 years ago  |  last reply 5 years ago

How do you change the AC frequency?

How do you change the AC frequency that comes out of the wall?

Question by Comhippy 9 years ago  |  last reply 9 years ago

Is there an easy way to change the electrical frequency? From 45hz to 60hz?

Is there an easy way to change the electrical frequency? From 45hz to 60hz?

Question by 9 years ago  |  last reply 9 years ago

Help converting 60hz to 50hz

I currently have bought an aquarium pump from the UK and am using it in the United States. I have bought a step up transformer that goes from 110v input to 220v output. The pump works, but is not functioning properly, it loses flow rate over time and gets pretty warm. One thing that I think may be affecting the performance is that the frequency difference between what the pump is rated at and what is supplied here in the US. What would be a cheap (<$100) easy way to test if it is the frequency issue? How would I convert it? Thanks!

Topic by brandon3rdstone 6 years ago  |  last reply 6 years ago

designing an LC4/LC5 package for mm-devices using Eagle CAD tools?

Hello every one, Since i am totally new to PCB designing and all these stuff, I want to know few things about Eagle CAD tools I will be designing a Frequency up-donwn converter as a University course project. out of many components selected for this project one of them is as follow. i have gone through designing of the LC4 package, i hope it would be fine, still i would like to know how to creat ground of a package, creating outline boundries of package (is it from wire or from rectangle, polygon??) and about symbols inside this package, i am confused about drawing them exactly and connecting them to each other (via wire or net or what??), should they be just symbol or e.g i have to draw even what is inside circuit of a mixer or amplifier etc.. I shall be very much thank for your kind help

Question by lali2 7 years ago

Using 433M-Transceiver-Module-E32-TTL-1W-SX1278-SX1276-30dBm-LoRa-Long-Range-433MHz

How do i use  433M-Transceiver-Module-E32-TTL-1W-SX1278-SX1276-30dBm-LoRa-Long-Range-433MHz with arduino uno, like schematics, codes, what is MO, M1 to transfer data as I can not find much about it. Cheers

Topic by laidlow7 1 year ago

Arduino + RF to create item/finder?

IDEA 1. I've got the idea to create this kind of project where people nowadays being careless and misplace their item. So to counter this problem, i want to create a device which can detect the object/item within an area/radius of the receiver and transmitter. 2. This is not only for item/object but also can be placed on your children just in case they are away from you thus this device can alert you in sound, sight ( blinking LED ) , and vibration. PROBLEM 1. Is it possible to only use 1 transmitter and receiver? 2. Just in case for future uses, can compass be implanted in this device where it will always shows to the transmitter? 3. Currently programming are very hard for me, where can i get reference for programming this kind of device?

Question by Isaace11 3 years ago  |  last reply 3 years ago

Testing Tesla coil frequency with a multimeter frequency (Hz) meter?

My multimeter can measure up to 20MHz and I was wondering if I could test the resonant frequency of my Tesla coil by running it (untuned) then having the multimeter attached to an inductor a few feet away?  Would this work or would I need some kind of small circuit attached to the multimeter as well? If I could do this would it work with the primary as well?

Question by The MadScientist 8 years ago  |  last reply 8 years ago

how to measure frequency in this circuit?

i want to measure the frequency of this flasher circuit but i always get a frequency close to that of the mains. I am using a wall wart. i changed some of the components to speed up the flashing but the frequency reading stayed the same. to check my multimeter i tried measuring the frequency of mains and the joule thief circuit and it looks like my multimeter is good. how should i measure the frequency in this flasher circuit?

Question by codestroy7 7 years ago  |  last reply 3 years ago

frequency of composite video signal ?

I try to configure a tv / video card on my computer to display input from composite video (yellow plug) input when i choose any of the inputs i still have to set the frequency (above). it should be some fixed standard frequency. what is it for pal b/g ?

Topic by 11010010110 10 years ago  |  last reply 10 years ago

555 pwm AND frequency controllable? Answered

Hello, I've been breaking my head on this for a while now, and still couldn't find a correct solution for this. I want to be able to adjust the duty cycle (pulse width) with one potentiometer, and the frequency with another potentiometer, using a 555 timer. Adjusting the frequency shouldn't change the duty cycle! (which is the problem in All of the circuits I find online). This is an example of a circuit I find online, many of the circuits look just like this one (see picture) Now, the problem is that when you increase the resistance of the potentiometer for adjusting the frequency, that makes sure you can never get 0% or 100% duty cycle anymore! or not even close to that. It's because increasing that resistance, also decreases the 'discharging current' of the capacitor, so it will also increase the discharging time when that's not wanted. Without R2 it works perfectly, from 0% to 100% duty-cycle; but with the frequency potentiometer it all gets messed up. It's a little difficult to explain, I'll try it with another example :) To get 0% duty-cycle (or something close to that, like 10%), you'll need to make sure the path for Discharging the capacitor goes near 0Ohm. Increasing the potentiometer for the frequency makes that impossible because it's in series with the capacitor's charging and discharging circuit. So that would also increase the discharging time while I don't want that. When the resistance of the frequency potentiometer increases, the duty-cycle gets variable between just something like 45% and 55% (example) so that's not good. Is there any way do do this? :/ Thanks in advance, Elecotrials

Question by DELETED_Electorials 7 years ago  |  last reply 2 years ago

Frequency of Laser Tag guns

Does anyone know if Laser tag guns use infared LED's emitting at a certain frequency, If so what frequency/range of frequency

Topic by thermoelectric 10 years ago  |  last reply 10 years ago

Radio frequency program for computer

I am trying to modify an old am fm radio, so that it can pick up transmissions from a walkie talkie. I know the frequency at which the walkie talkie operates, but I can not tell the frequency of the radio when I am adjusting it. Is there any computer program, or something that can tell me what frequency I have?

Topic by Sedgewick17 10 years ago

Changing the frequency of Ultrasound Massager ?

Is it possible to convert one of those existing portable Ultrasound unit thats use ( 1- 3 mhz ) to lower frequencies i.e.  35 - 350 khz  or build one form scratch ? thanks hele

Topic by hele 8 years ago  |  last reply 8 years ago

Can the arduino detect frequencies?

I want to make a spectrum analyser and I want to use a micro controller, but I don't know how. I want to know if the arduino (any one) can split up the different frequencies and output them, so I can use it as an input to an LED driver (LM3915). This will allow the LEDs to be at full brightness and respond to the output of the arduino, if the frequency filter is possible. If not, I will use a series of bandpass filters instead. I want to make an 8 band spectrum analyser. I just thought that using an arduino would be cheaper. Thanks. The schematic I will be using:

Question by knektek 6 years ago  |  last reply 6 years ago

variable frequency drive construction?

Hello i am working on a go kart but instead it will be powered by a 1/3 horsepower split phase AC motor. it operates off 768 watts and i am curious in using a Microcontroller and a high power H bridge to control it. can anyone help me or give me an idea on how to step up 12v dc into 120v dc and then using the H bridge to generate the frequency and also where to find some NPN transistors that can handle it and how to possibly reverse the direction of the motor?

Question by luig 6 years ago  |  last reply 2 years ago

microcurrent frequency specific device?

How To Create Frequency Specific Microcurrent? I am looking to build a two channel (A/B) microcurrent (allowing from 20 - 600 microamps) with selectable frequencies ranging from 3 to 970 Hz). This is based on a medical device that I'm looking to replicate. I've figured out some of this but again, considering the wealth of knowledge here I'm sure some would know the best way to build this. here are specifications Description Device Specs Frequency Range: 0.1 – 999.9 Hz programmable Wave Form: Square pulses Duty Cycle: 50% Current Intensity:  20μA to 400μA Constant current generator Output Polarity: Programmable alternating, positive or negative Output Load Resistance 0 to 100K ohm Output Channels: Two fully independent channels Output Connection: 3.5 mm mono phone jacks Programming Port: micro-USB Memory: Professional-up to 999 programmable protocols; Patient: up to 99 programmable protocols Power Supply: (2) AA alkaline batteries Dimensions: 5.1 x 3.2 x 1.2 inches Weight: 6.42 oz here is the link i am following

Question by kedarg2 1 year ago  |  last reply 5 months ago

Bluetooth vs Radio Frequency Answered

This is a 3 part question: 1. I am a bit confused. Radio frequency covers 3KHz to 300GHz, so it basically includes bluetooth(2.4 GHz). Why is it that some people talk about bluetooth as something not relating to RF. Do they have different transmission methods? WIFI is also @ 2.4GHZ. What is the distinction between WIFI and bluetooth that makes them so different, covering different ranges, and being able to send different amounts of data at different speeds. I always thought it was the frequency of the wave but WIFI and bluetooth are the same yet they are so different.  2. I am building a project. I need to send data wirelessly. The data is very simple just to turn on or off a series of leds. A friend of mine told me to use radio waves. What does he mean by that exactly since radio range is huge. Is he talking about 40MHz like the RC cars? 3.Bluetooth or RF(again im assuming this to be the same one as RC cars since i will break apart an RC car to remove the transmitter/receiver)Which method consumes less power to send the same amount of data. Distance will not be over 10 meters so i'm not worried about that.  Thanks for the help everyone, much appreciated! Chris

Question by Chris414 6 years ago  |  last reply 3 years ago

Radio Frequency Proximity Detector

Hello, Does anyone have an instructable for building a proximity detector based on a radio transmitter and receiver? Or some other wave based method? I've viewed the IR proximity detector here on this site, but I need a transmitter/receiver based one. Yes, this is for my pet. I have 2 cats and 1 dog. I need to keep the dog out of the same areas that the cats are allowed to go into, thus the proximity detector needs to be specifically tuned to the dog. Distance does not have to be far, anywhere from several inches to a couple feet. Appreciate any comments or instructables! Thanks, Eric

Topic by riccarr 12 years ago  |  last reply 8 years ago

What happens when you induce two currents of differing wavelength on the same line? Answered

If I induce two currents of differing wavelengths on a single conductive body, say an iron pipe for example, how can I calculate what the resulting signals wavelength will be? Is it as simple as taking the root mean square of the frequency of the signals? Any ideas for calculating the voltage of the final signal? ------------------------------------------------------------------------------------------------------------------------- Example: Signal 1: 60hz at 100v Signal 2: 75hz at 100v RMS frequency sqrt(((60^2)+(75^2))/2) =  67.9153 ------------------------------------------------------------------------------------------------------------------------- Thanks  a bunch!

Question by paulcauchon 8 years ago  |  last reply 8 years ago

Measuring oscillation of a multi tool

I have a harbor freight oscillating multitool that is advertised as oscillating between 10k and 20k oscillations per minute. In reality to speed control goes from 0 opm to an unknown value. I’m trying to set the tool to oscillate at 35 Hz. What is the best way to measure the frequency of the tool and set it to 35 Hz?

Topic by rednax718 1 year ago  |  last reply 1 year ago

Determining frequency of processor And AVR O.C. ?

So This question has two parts.... i need to measure the frequency of a computer processor.....and an avr microcontroller........ actually i want to know weather it is possible to connect a arduino to a pc's processor through wires or an avr through wires to a secondary system like an arduino which will measure the frequency....... and is it possible to overclock an avr ? if yes , then how can i ?

Question by _Boltz_ 2 years ago  |  last reply 2 years ago

How to make a frequency converter? 2.4GHz to 600Hz

Greetings, I would like to know how to make a frequency converter. I want to convert the 2.4 GHz from a WiFi transmitter to one fourth or 600Hz which is in the newly freed up white space area for greater range. Anyone know where to find schematics for this, or make schematics? Is the circuit complicated? Thanks

Topic by NeuroPulse 8 years ago


Interested in knowing how to repel mosquitos using a frequency generator. Or can someone guide me in building a frequency generator to attaract mosquitoes (not kidding) so that i can lure them into a trap and kill them. Looking for genuine answers please.

Question by ramki695 9 years ago  |  last reply 7 years ago

Trying to create a circuit to allow me to adjust the frequency of AC power

I'm trying to design an EM field generator with adjustable frequency. I've got most of it figured out, but I can't seem to find anything about how to create adjustable frequency AC power. I've got two designs I'm working on, one that is DC powered and one that is AC powered, but the best I can do on either ends up with a 60Hz EM field. I'm looking for adjustable frequency, ideally from 0.1Hz to 50kHz, although I'll be pretty happy to even get any range of frequencies at all. The range from 0.1Hz to 500Hz is the most useful and interesting in particular for my purposes, but any help on figuring this out at all would be much appreciated.

Topic by PsychoHazard 8 years ago  |  last reply 8 years ago

Audio Detector

Is there some type of electrical component which detects high frequency sounds like those mosquito ring tones? I've looked around and seen things which apparently detect high frequency radio waves, but that isn't really what I want (at least I don't think it is). Thanks in advance.

Topic by brickzima 10 years ago  |  last reply 6 years ago

How can you generate a signal up to 150 MHz with an AVR?

How could I generate a signal, whose frequency could go up to 150 MHz? I'd like to use an AVR, but how would I do that?

Question by DemonDomen 10 years ago

Where can I buy a cheep four or eight channel bandpass filter?

I want to build device that will contain LEDs. Each LED will light up to a different frequency. I believe this is the part that i need for this, is it not? if so does anyone know where to get them?

Question by jmkloz 9 years ago  |  last reply 9 years ago

Passive Amplifier Optimized for a Single Frequency

First off, I know next to nothing about acoustics or sound science of any kind.  My idea is to make some sort of passive amplifier, like a horn, that is optimized for a single frequency, I'm thinking about 4KHz.  I have no clue how to go about designing such a thing and all the info I found on google was too complicated for me to understand.  Does anyone has any starting points for me or just general advice/suggestions?  Or, if you're feeling generous and/or really bored, would anyone like to design such a thing for me? Thanks ~Josh

Topic by Josh_Blackburn 1 year ago

Antenna length for a frequency modulated signal.

I  am given to understand that the length of an antenna is proportional to the wavelength of the signal that is fed to it (a quarter wavelength, for example). In the case of a signal modulated by amplitude, the frequency (and therefore wavelength) of the carrier wave remains unchanged. However, in the case of a signal modulated by frequency, the signal fed to the antenna will vary in frequency (and, therefore, wavelength). My query is this : how would one go about calculating the length of an antenna for a frequency modulated signal? Its frequency is not constant, so to construct an antenna of say, a quarter of the wavelength, would be impossible. I thank you in advance for your assistance. AlexHalford

Question by alexhalford 9 years ago  |  last reply 9 years ago

I want to generate 2.4GHz frequency

I want to generate 2.4GHz frequency and transmit as well as received in liquid Which probe can use for transmit and receive?

Question by vivekbarage 3 years ago  |  last reply 3 years ago

What different frequency meter and counter? Answered

Dear all.. Please help me to know : what is difference frequency meter  and  counter between 2 devices  (please see photo) Thank you so much.

Question by lam 3 years ago  |  last reply 3 years ago

Frequency driver HV generator circuit Answered

Dear all... At this circuit please help me to know: - How many cycle (frequency)and duty cycle : time high and low  (percent) for  better driver this circuit. Sorry for more question.If I change other transformer (ferrite core)and driver by 555 timer, frequency  and duty cycle must   be modifier or not ?                                      Thank you in advance

Question by lam 5 years ago  |  last reply 5 years ago

Arduino to control frequencies with induction coupling?

I want to experiment with inductive coupling, I have made two similar pancake coils of 16 turns of 12 AWG wire(I had it around ) . Now I need to generate a frequency, I know I can generate one with an arduino but I want to generate one to work with the 12v input from a computer PSU to make it more practical. Any way to do this? I'm kinda new to coils/frequencies. 

Question by Tom101222 5 years ago  |  last reply 5 years ago

how to generate the 2.4 GHz frequency ?

I am designing the anti drone device which can jam the drone in operating condition and make it inoperable. but i am struct with the problem that how to generate the 2.4 GHz frequency using voltage controlled oscillator.

Question by AbhinavD9 1 year ago  |  last reply 1 year ago

I wanna frequency converter transformer ?

Hi Everyone I wanna to know where can i get frequency converter transformer that it's input is 2 wire (220v-50hz) and it's output is 3 wire where the voltage between any wire and com. is 110v and between the two wires is 220v

Question by MohamedE7 4 years ago  |  last reply 4 years ago

What frequency to use for a gaming steer?

I have an old gaming steer which is not compatible with win 7+, and I can’t find its drivers either. So, im manipulating it on my own, and will use 4 IC NE555 and a potentiometer in astable mode to press [w/s/a/d] with I-don’t-know-what range of frequency. Is there anyone could suggest me use what range of frequency? I thought 700–4000 Hz would be ok. But I have no idea if it is, or not

Topic by Nimasa77 1 year ago  |  last reply 1 year ago