How to increase the range of ultrasonic object Detector

[Alen]

Hello all

I've connected the circuit below which is uktrasonic object detector...

but the maximum range it covers is 20 to 25cm only ... i want to ask if any one can help me how to increase the range..... thanks

this is the circuit

 

[audioguru]

1) Increase the supply voltage of the transmitter to up to 15V. Then the transmitted ultrasonic will be much louder.
2) Parallel the 3 unused inverters in the transmitter with the output inverter for much higher output current to drive the transducer louder.
3) Change the 1st opamp circuit in the receiver to a non-inverting type, It will have a much higher input impedance and hence much more gain. In fact it can then have any amount of gain. The inverting existing circuit has a fairly low 10k resistance loading-down the output of the microphone transducer. Since the microphone transducer is high impedance, the gain of the inverting opamp is very low.
:lol:

 

[Alen]

Hello audioguru

thank u for ur help and giudance

I followed the steps that u mentioned 4 increasing the range( actually i did 1st and 2nd steps) and it works....

but the 3rd step which is converting the inverting op-amp in the reciver part to the non-inverting isn't clear 2 me.... I understood the purpose of using noninverting rather than inverting op-amp... but I don't know how to do it ... i know that the terminal 1 should be grounded .. if i am not wrong ... but I don't know what is the specification that i have to consider ... I ask u if u can provide me more details about the 3rd step ......

thnks again .. i appriciate ur help

kind regards

 

[Optikon]

Hello audioguru

thank u for ur help and giudance

I followed the steps that u mentioned 4 increasing the range( actually i did 1st and 2nd steps) and it works....

but the 3rd step which is converting the inverting op-amp in the reciver part to the non-inverting isn't clear 2 me.... I understood the purpose of using noninverting rather than inverting op-amp... but I don't know how to do it ... i know that the terminal 1 should be grounded .. if i am not wrong ... but I don't know what is the specification that i have to consider ... I ask u if u can provide me more details about the 3rd step ......

thnks again .. i appriciate ur help

kind regards

Write the transfer function from R1 to R2 through the OA that guru talks about. Now just implement this function with a non inverting setup for less loading of the input receiver. You can find non inverting OA topologies on the web. Or someone will post it here. Are you familiar with amplifier design with opamps?

 

[Roff]

If you want a gain of 100, you will need a faster op amp. Choose one with a gain-bandwidth product of at least 10MHz.

 

[Alen]

hi Ron

Does replacing the exciting op-amp with this type(10Mhz) need any further change to the circuit? !!!

i am still waiting for non-inverting op-amp circuit that can be replaced by the exicting one...

thnk .. u guys

 

[Nigel Goodwin]

hi Ron

Does replacing the exciting op-amp with this type(10Mhz) need any further change to the circuit? !!!

i am still waiting for non-inverting op-amp circuit that can be replaced by the exicting one...

Haven't you heard of google?.

Here's one site about opamps **broken link removed**.

 

[audioguru]

Hi Alen,
1) I used a much faster opamp that still works at the very low supply voltage of 5V, and its inputs still work at ground. Its power supply current will be a few mA.
2) I made the 1st one non-inverting with a high input impedance and a gain of 101.
3) I added a bit of hysteresis to the output opamp so it doesn't oscillate at its threshold voltage.
Try it, you'll like it. :lol:

 

[Alen]

tnx,,, alot guys

thanks for the link...Nigel Goodwin... (by the way ...I know google :wink: )


audioguru , u r great ,man ...

I 'll try it .. and .. let u know the result .. thanks alot again ..