Need help in a circuit??!!

[RRR]

Hi all... am new around here...

Well, I have finished fabricating the sonar circuit which I got its schematic from: **broken link removed**

Unfortunately, it does not work and am not professional in electronics, so I can not identify the problem. The problem is, all the LEDs are slightly lit, and it stays like that even if I move something near the trandsduecers.

I gave the circuit to someone to check and he told be that the receiver receives the signal, how ever it does not reach Q8 transistor? He says that the transistor I used is wrong and that it should be a pnp, not npn, is he correct? And which transistor should I use for Q8? Or do I have another problem?

Thanks

 

[Roff]

Read the section in your link called "Modifications". It tells what to do with Q8. Also check out this thread for a backup alarm I designed. Here is the reply I got from Steven - he should have posted it instead of PM'ing me.

steven_first_2001 wrote:

Hey Ron, Remeber me? Well I built the backup alarm circut and it works great! My teacher was overly happy with the backup alarm so he gave me extra points in class. I got my report card and I had 110% in class! I just wanted to thank you for all of your help.

The down side of this design is it uses a commercially available sonar transceiver, which is probably much more expensive than 2 transducers.

 

[heru]

helloo...

i want to make power regulator with lm 7805 and 2SA1302 for supply cd room. It use to regulate 12 volt to 5 volt with 2 amphere current.
thank's

 

[RRR]

Thanks A lot RON H... I do not remember seeing the modification part, but its there!!!!!

I will modify my circuit and see what happens, hope it works...

Thanx again

 

[TillEulenspiegel]

Hmmm, seems a pretty straightforward circuit. I think your friend is mistaken, the directions call for a bc109a or b, that's
a low power NPN signal transistor-European number . You could prolly use any small signal NPN transistor.

The problem now...How does your friend know the signal never reaches Q8? If the signal disappears in an electronics device the thing to check is where it disappears, because nothing farther down the path will work , so if its not reaching Q8 the problem is most likely before Q8. The description of the problem tho sounds like theres something else going on . If theres no signal the LEDs should not light at all. This could be caused by different things. One is that both U3 and U4 are static sensitive and can be blown just by handling them. The other possibility is that the enable pin ( 13 ) is at ground potential all the time and what your seeing is actually U3 counting at 40kHz and lighting the LEDs. Their dim because @ 40kHz they don't have the time to turn fully on. That could be U4 being blown or something wrong with the audio circuit. The way to check that is to dis-connect pin 13 of U3 from the circuit and connect it to V+ with a 1k ohm resistor and see if the LEDs turn off. I'ts kinda hard to check circuits @ 40 kHz without a scope but it can be done. Another thing ...when I prototype a circuit with CMOS IC/s I use sockets ..it's soo much easier to service and trobleshoot.

 

[RRR]

Well I did the modification but with no luck... well it was working before but with a lot of LEDs were flickering and it was not that accurate before the modification, then I used another power supply and from that day all the LEDs staid slightly lit...

Thanx TillEulenspiegel for the detailed info... I will try to check or even replace the ICs and I will put them in sockets... also will try to get my hands on a scope for better testing...

I use one 8Volt power supply to supply the whole circuit even the ICs... Could this create a problem??

 

[gerty]

Are you running the 8 volts thru the regulator? If so check the voltage on the output, it may be low..

 

[TillEulenspiegel]

What Gerty said, If your using a 9VDC or AC source it wont pass the full 8-9 VDC, use a 12V source. Try the circuit with a 12VDC battery