Need help on reset / delay circuit

[mery77]

Hello everyone, I just recently just bought a device that allows me to receive GSM (cell phone signal) in a site where cell phone signal is not detected by regular cell phones. The device works fine for approximately 15 minutes and then it freezes. By turning the device off and on again it works again for another 15 minutes. I then installed a wireless phone that allows me to move around and still be able to use the phone. However, since the signal device only works for 15 min. approx., I have to go and reset it for it to work again. I have tried many devices and this is the only one that I've found able to detect some signal (therefore I would like to make it work). The device works with 110v input. I wonder if there may be a simple circuit that could allow us to leave this device connected to the 110v power permanently and have it reset every 10 minutes (i.e., turn it off and on) so that I don't have to go and reset it every time I want to use it. It would be ideal if the circuit could also wait 2 seconds before turning it back on. Can somebody help me design this circuit? A friend told me to buy some parts and I have bought some including a 555, a 556, and a protoboard. However, if these are not needed I can take them back. Thanks a lot...

 

[blueroomelectronics]

Since it's new why not get it repaired. It's obviously defective. What model / make is said device?

 

[mery77]

Thanks, the device works fine in the city, where signal is not a problem. I´ve already tried many devices already and they all work perfectly under good signal conditions. Under almost no signal conditions, this FWT GSM device is the only one that detects some signal. Therefore I really need a circuit to solve my problem, can you help me with it? The device is not defective since it works perfectly under normal signal conditions.

 

[blueroomelectronics]

What is the make and model of the device?

 

[mery77]

Model: GSM FWT (FWT 188B). I really need the circuit, can you help?

 

[blueroomelectronics]

No circuit required. I has an external high-gain antenna option and is probably resetting every 15 minutes because it can't hold on to a signal.
Just buy the optional antenna.

 

[mery77]

Thanks again =) it already has the optional antenna, can you please help me with the circuit? I already tried all sorts of gadgets, antennas etc.

 

[blueroomelectronics]

The 555 is not very good at long timing intervals, a CD4060 would be a better bet for 15min. The outputs are 50% duty square waves you'll have to add some logic to get the 15min on 30sec off you're probably looking for.
Google CD4060 for datasheets and schematics.

 

[Nigel Goodwin]

Why not just change to a network that provides better coverage?.

 

[eblc1388]

Hi Mery77,

Someone posted this circuit in another forum, may be it is suitable for your usage. Best of luck.