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1  Using Arduino / Project Guidance / Re: 433mhz *RECEIVER* arduino - How to deal with interferance? on: Today at 05:56:32 pm
The gibberish you are seeing is simply thermal noise converted into a 2 state indication.
Even in a faraday cage , the receiver will still generate the same gibberish as all radio receivers no matter how good they are
have a RF front end which has a noise figure > 0, and is operating above 0 K.


The basic methodology to making these receivers work is to send data to them in a form thats easy to pick out from the noise.
A sequence of 1 - 0 - 1 - 0 transitions at the start, usually around 20 + will do , followed by a pattern thats differant , such as
1 -0 - 0-1 , then whatever data you want to send.
Using a Manchester Coder at the sending end will improve your chances of receiving anything.
But as others have mentioned, you get what you pay for.
These receivers are extremely simple.
Have a good read about Virtualwire and how it works , and look at the sourcecode.
2  Using Arduino / Project Guidance / Re: Key fob jammer for my Volkswagen car on: September 30, 2014, 09:32:20 pm
How old is the car?
Most modern cars use a rolling code key fob to unlock the car, and these types of key fobs cant be copied by code grabbers
as the code changes everytime the button is pushed.
Unless your car has a very old style locking system, it would be easier to simply upgrade the locking system to a rolling code type.
3  Using Arduino / Project Guidance / Re: Best way to power Arduino Uno with 12V Lead Acid + monitor battery charge on: September 30, 2014, 01:18:18 am
The cheapest 12V to 5V switching regulators you can find are cigarette lighter USB adapters for cars.
They can provide up to 2A at 5V which is plenty for an Arduino.
Ive seen them for as low as $2 in places like the Reject Shop.
Auto shops also have them.
4  Using Arduino / Networking, Protocols, and Devices / Re: Problem with module rf receiver 315mh T4 on: September 25, 2014, 04:37:09 pm
What does the transmitter module look like?
5  Using Arduino / Networking, Protocols, and Devices / Re: Problem with module rf receiver 315mh T4 on: September 25, 2014, 03:40:43 am
What are you trying to do?
The picture you have shown looks like a receiver and a decoder , so it doesnt need , and wont work with virtualwire.
6  Using Arduino / Motors, Mechanics, and Power / Re: How can I know the frequency of a RF module of motorized blind ?? on: September 21, 2014, 06:21:12 pm
There are more than 2 possibilities.
Could be either 315 or 433 Mhz, but could also be AM or FM.
You need some kind of scanner to tell the differance.
7  Using Arduino / Project Guidance / Re: RC Switch 433MHz not receiving signals from flash trigger on: September 16, 2014, 07:13:30 am
From the description of the flash unit , its using FM, which means the receiver you have simply wont work, as its
an ASK (AM) receiver.
8  Using Arduino / General Electronics / Re: 0 Voltage from power supply when connected to peltier on: September 15, 2014, 06:13:40 pm
What is the specs of the peltier, ie power rating at what supply volts.
Laptop power supplies are protected from overcurrent and will shutdown if overloaded.
Most common peltiers run off 12V , so 19V is far too high.
9  Using Arduino / Project Guidance / Re: RF Receiver Range with Arduino on: September 13, 2014, 07:19:41 pm
Measure the voltage on the receiver board.
Needs to be very close to 5V .
If the voltage is low , (less than 4.9 V) the receiver will appear to be deaf.
10  Using Arduino / Project Guidance / Re: Working with RF Module on: September 13, 2014, 07:06:40 pm
Those modules are based on the SC2262 / SC2272 encoder decoder chips and are used for simply sending a 4 bit nibble
from transmitter to receiver.
They use the same protocol as the RC switch library, as they are often used for remote control power points.
You cant send hi speed data though, as the decoder chip takes about a second to decode a valid frame.
11  Using Arduino / General Electronics / Re: Can I drive an N-MOSFET with an NPN-Transistor? on: September 07, 2014, 06:34:04 pm
Those are inverting drivers.
They will work , but will reverse the PWM output state  of your Arduino so that PWM = 0 will be full on.
Try and find a non inverting driver.
12  Using Arduino / General Electronics / Re: Can I drive an N-MOSFET with an NPN-Transistor? on: September 06, 2014, 06:57:00 pm
Ideally, the best way to drive hi power fets is with a dedicated FET driver, like one of these.
http://www.futureelectronics.com/en/technologies/semiconductors/analog/drivers/mosfet-igbt-drivers/Pages/2809358-MIC4422YN.aspx?IM=0

They are pretty cheap, usually around $1 or less, have sufficient current capacity (9 amps for this one)  to turn a FET hard on and off in under 10 ns and can be driven by either a CMOS or TTL input , so you can drive them straight from an Arduino output pin.
Fet drivers are pretty common ICs , so lots of manufacturers make them.
13  Using Arduino / Project Guidance / Re: Getting data from 10 Arduinos wirelessly on: September 06, 2014, 04:44:11 am
How often will the wireless transmitters be transmitting?
This type of problem depends entirley on how reliable you want the project to be.
Can you afford to lose data?
A Master Slave arrangement is the best option , but does require bi directional transmission.
14  Using Arduino / General Electronics / Re: Can I drive an N-MOSFET with an NPN-Transistor? on: September 02, 2014, 06:29:51 pm
The IRFZ44 has an input capacitance which ranges from 1500 to 2300 pf, which is not unusual for hi power fets.
If you want to PWM the fet, its important that whatever is driving the gate can provide enough current to charge
the gate capacitance in a much shorter time than the pwm rate, otherwise the fet wont ever actually turn on hard
and will get hot.
15  Using Arduino / General Electronics / Re: 315Mhz transmitter, push button version on: September 02, 2014, 04:56:00 am
The cheap 433.92 Mhz ASK radios do not transmit the state of the data pin.
They only transmit changes in state on the data pin , but the data must be continually changing.
You must have either a Micro controller or a data encoder like an SC2262  to make them work.
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