Audio only variometer

I have not built anything for years, since my amateur radio days but I want to build myself an audio only vario. A vario is an instrument that is used when flying, in my case a paraglider, and it tells you if you are going up or down. Works by sensing air pressure, and normally they have also a built in altimeter and flight recorders and alsorts of whistles and bells. I only want one that has audio output, not to a display of any sort. Has anyone got any idea where I can find a circuit for this???

You can make a fairly simple audio oscillator that has the pitch of its tone or the pitch of its beeping varied by a signal from the variometer. It might drive you crazy.

But you would need to post the schematic of the variometer for us to see where to connect the V
You might need to measure and post the voltages in the variometer circuit.

Hmmm, I want to build the whole thing from scratch, but don't have the knowledge, I was hopeing someone would have a circuit I could follow.

Start with the input. You'll need a differential pressure sensor that's capable of both positive (descending) and negative (ascending) pressure indications. Both ports of the sensor will be open to ambient air pressure. One port will have a large opening, to immediately detect the ambient air pressure. The other port will have a very small opening, so the change in air pressure is only gradually detected. This sort of acts like a "memory" of the altitude you "were" at. The the magnitude and polarity of the sensor's output will give you direction and rate of change in altitude. The sensitivity of the sensor and the port restriction will have to be worked out for the rates you are looking at.

Following the sensor you will need an amplifier/offset-stage driving a voltage controlled audio oscillator, followed by an interface for your intercom/radio.

I agree with audioguru that the tone would get awfully ear-itating.

But first, work out the pressure sensor.

Just did a quick Google on: vertical speed indicator circuit ...and got **broken link removed**

Ken (haven't flown in years)

I was an air Cadet.
When I was 14 years old I was at the controls of a twin-engine Expediter. I tried a loop but it shook then stalled. I tried a barrel-roll but it didn't doo dat.
I think I nearly broke the wings off. I wasn't allowed to try a takeoff nor a landing.

Now I fly two small IR-remote-controlled toy helicopters usually in the house but sometimes outside. They scare my wife and dog.