Whites Surf PI schematic

[kt315]

No MPSA14, how substitution?
I only BC548 how Darlington?

if you can not find Darlington around... use two N-P-N type transistors according the structure you see above. there is not problem to get a Darlington...connect them both what you see on the picture.

[ivconic]

No MPSA14, how substitution?
I only BC548 how Darlington?

Have you BC517?

[bernte_one]

No MPSA14, how substitution?
I only BC548 how Darlington?

was it bc227 turning 180 degree? it dont know

[yhl]

No MPSA13, how substitution?

No MPSA14, how substitution?
I only BC548 how Darlington?

[ivconic]

Hi bernte, ivconic and TH Jim.
Thank for the answer.
Sorry for delay, but i have been on hollidays and i didn´t have internet, is a small town on the Beach.
I used a piezo of 4cm (before piezo 2cm) and change resistor of 33 ohms for other 4.7 ohms. Thanks for the idea ivconic
Is fantastic underwater perfect listening
Is a nice detector. Works perfect under water

Greetings to all

[hispalba]

Hi bernte, ivconic and TH Jim.
Thank for the answer.
Sorry for delay, but i have been on hollidays and i didn´t have internet, is a small town on the Beach.
I used a piezo of 4cm (before piezo 2cm) and change resistor of 33 ohms for other 4.7 ohms. Thanks for the idea ivconic
Is fantastic underwater perfect listening
Is a nice detector. Works perfect under water

Greetings to all

[TH Jim]

I also had low volume on my surf pi - so i changed the audio output stage to that of the Barracuda. Now its deafening!!

Have a look at the Barracuda thread and try it

Good Luck

Jim.

[ivconic]

Hi, I need help. My surft works fine, but the sound is very low. I built two surf. Greetings. Some pictures of my box.

Very nice work!

You want louder audio?
Change that resistor 33 ohms. Put lower value, experiment with values bellow 10 ohms. Or omit it.... But sometimes this can burn transistor or Volume potentiometer. So is better to omit potentiometer and put fixed value. Find best value that will suit you.
Usually i do omit potentiometer and instead 33 ohms i use 4.7 ohms. But this depends on speaker resistance. If 32-50 ohms speaker (and over) is used than you don't have to worry...
Better solution is use of piezoelectric speaker. Than you can freely omit potentiometer and resistor.

[bernte_one]

hello hispalba

i see your pipe is from clear material have you thought already about placing a single white clear led at the audio output ?

[hispalba]

Hi 6666
Thaks. Yes it is a waterproff box. (5bar)
I haved used 8 ohm and 32 ohm speakers, sony earphones and piezo.
But in the surface and in underwater it is sound very low.
Regards.
One speakers picture.

[maikl]

Probably used in speaker 0.5 W from the 8 ohm...

[6666]

Thats a nice box, looks water proof

what are you using for the sound ?

[hispalba]

Hi, I need help. My surft works fine, but the sound is very low. I built two surf. Greetings. Some pictures of my box.

[6666]

Thanks MIKE I have been wanting to know what switch 2 did as well

[mikebg]

I want to know What is S2 for? What is its function?

The switch S2 can be used not only for battery test. It helps to adjust maximal possible volume when appears a large or close target causing very strong signal. The operator should hold the S2 pressed and adjust volume with R33 below his level of deaf. However if the battery is discharged, at S2 pressed, the sound will not change because there is no current through D5.
If I was designer of this circuit, I will put a resistor R36 as shown below to compensate leakage current of D5.