The topic is quite clear ,So i was wondering how we can make such a circuit !

 

Hello,

Can you give us more info on the circuits?
How much current is flowing in the "origenating" circuit?

Bertus

 

Actually the topic isn't clear. Don't assume, it doesn't work.

I assume you want something like the output of a 555 to power a second circuit. Is this even close?

Schematics and examples are your friend.

 

The originating current is about 5 A

 

Hello,

Can you post a schematic of the originating circuit?
Is it possible to connect anything to the circuit?

Bertus

 

here is my circuit : http://www.electronicsforu.com/elect...e=Mobile%20Bug

 

Hello,

The mobile bug you show in the link is never drawing 5 A.
Can you give us more info.
With the info provided we can not do anything.

Bertus

 

Hello,

The mobile bug you show in the link is never drawing 5 A.
Can you give us more info.
With the info provided we can not do anything.

Bertus

Actually my aim is to amplify the PD across the LED terminals currently its just 0.1 V!

http://www.physicsforums.com/showthread.php?p=2853797

 

A simple op amp such as the LM358 can amplify a small voltage like that, just set the gain to 10. Since your talking LEDs I am assuming DC voltage.

Actually my aim is to amplify the PD across the LED terminals currently its just 0.1 V!

http://www.physicsforums.com/showthread.php?p=2853797

PD? As in photo diode? If it is how does it apply with this?

 

A simple op amp such as the LM358 can amplify a small voltage like that, just set the gain to 10. Since your talking LEDs I am assuming DC voltage.

Yes it is DC voltage but 10 time higher will not help 50 times is required !!

 

So change the value of the resistors. I'm assuming you know how op amps work.

The reason suggested a LM358 is it can go very low to ground.

A LM393 is a comparator, it can do the same thing, but it does not have an analog output. It is strictly on or off. It has an open collector output with an absolute max current rating of 16ma. Less is better, much better.

 

Hello,

I have some doubts with the circuit provided.
The CA3130 will not work with the RF signal from the phone.
Also the desciption in C3 is very strange, the capacitor wit its leads will never meet the frequency as given.

Here the circuit uses a 0.22µF disk
capacitor (C3) to capture the RF signals
from the mobile phone. The lead length
of the capacitor is fixed as 18 mm with
a spacing of 8 mm between the leads to
get the desired frequency. The disk ca-
pacitor along with the leads acts as a
small gigahertz loop antenna to collect
the RF signals from the mobile phone.

Bertus

 

Here the circuit uses a 0.22µF disk
capacitor (C3) to capture the RF signals
from the mobile phone. The lead length
of the capacitor is fixed as 18 mm with
a spacing of 8 mm between the leads to
get the desired frequency. The disk ca-
pacitor along with the leads acts as a
small gigahertz loop antenna to collect
the RF signals from the mobile phone.

This is a blast from the past! Just after the Korean War, lots of military components went on the surplus market. A man who styled himself "Madman Muntz" started putting out a line of very cheap TV's using surplus parts.

The fun part was that many of the capacitors were old so-called "body end dot" types in phenolic packages - see the reference for "postage stamp" caps - http://en.wikipedia.org/wiki/Electronic_color_code . The individual capacitances were weenie, but could be made useful by soldering together 5 or 6 of them (possible in the days of point-to-point construction).

Then he got carried away by finding out how many components could be left out and still have the set work. This led to the use of lead dress as a means of adjusting reactances in the set. It also meant they became effectively unrepairable, because disturbing the runs of wiring tended to make the set stop operating.

Found a reference - http://www.freeenterpriseland.com/MUNTZ.html

 

Then use different values in the op amp circuit to achieve the desired amount of gain.