Circuit Info Needed: When state goes from 5V to 0 VDC output goes to 5 or 9 VDC?

[Satcom]

Hello,

I am wanting to build a circuit which when a 5 VDC input goes to zero volts (not necessarily ground) the circuit produces 9 VDC output of up to 100 ma of current from a small "transistor" battery. Does anyone have any ideas? I would like to also be able to adjust the output from 5 to 9 VDC.

This might seem a bit strange, why would I want to produce 5V when 5V goes to zero? I need to use this for when the radio signal into a UHF PIC receiver goes to zero and subsequently the output of pin D1 goes from 5 VDC to zero volts (or close to it). I want to build a solid state circuit which will produce a voltage when that happens to cause an alarm in the form of a voltage output; the full 9 VDC battery voltage of the device. I could do this with a normally open/NO relay too by keeping it energized when the signal was present and then when de-energized close to pass voltage to another device, in this case a piezo buzzer, but I don't want to suffer the continuous current draw of the coil if using a magnetic relay.

 

[ericgibbs]

Hello,

I am wanting to build a circuit which when a 5 VDC input goes to zero volts (not necessarily ground) the circuit produces 9 VDC output of up to 100 ma of current from a small "transistor" battery. Does anyone have any ideas? I would like to also be able to adjust the output from 5 to 9 VDC.

This might seem a bit strange, why would I want to produce 5V when 5V goes to zero? I need to use this for when the radio signal on a PIC receiver goes to zero and the output D1 pin goes from 5 VDC to zero VDC. I want to alarm when the signal goes away and need to produce some voltage when the 5V disappears.

hi,
A LM393 comparator could be configured to detect less then 5V and raise an output to 5v or 9V, you would require a MOSFET or transistor on the comp output to give 100mA.

 

[Satcom]

Thanks much! I guess I have to use a logic device for this one or build a circuit with lots of transistors myself. I will look into the LM393, appreciate the feed back.

If anyone is looking for some good RF and Satcom technical info, here's a link to my online notebook: http://www.imageevent.com/qdf_files/technicalgoodies

Chris

 

[magnatro]

this is the out put of the simulation


View attachment level converter.pdf

these may help you....

 

[ronv]

Driver

If I understand you right you want the buzzer to go off when the input goes low.
Here is a transistor implementation.

 

[Satcom]

Thank you very much, those do help me because I'm in Afghanistan and it takes a long time for mail to reach me, but I do have transistors and resistors and can build this quickly.

Regards,

Chris, civilian supporting the USAF

 

[4pyros]

ronv; You need to level shift and invert. The output of your circuit does not apper to invert. Andy

 

[magnatro]

View attachment 47527

this is the out put of the simulation


View attachment 47526

these may help you....

 

[Satcom]

Thank you!