Surf Pro Kit

[dime196604]

This is the only wave I can get while trying to set the damping. the only part that changes is the little negative peak on the bottom. so I do believe I am doing something wrong here

[dime196604]

Now i have a question on sting the onboard delay trimmer. What is the best way to go about this. I have tried doing it by ear but i don't really hear a difference in signal strength. Is there another way to set the delay? Also after finding the perfect delay setting, should i go back and recheck the offset? Or will it stay the same once i have set the offset to 0v? I am close to being done with this project but not there yet.

[Qiaozhi]

Maybe a dumb question here. Does the polarity of the headphones or speaker matter when you wire it up to this board? If so what would be the best way to figure out what pin is positive and negative on the board?

Neither headphones nor speakers are polarity sensitive.

Speaker polarity only matters in hi-fi systems, where you want the speaker cones to all push or pull the air in the same direction. Otherwise, if you send the same signal to both speakers and one pushes while the other pulls, you can hear some strange phasing effects. The same applies to systems with more than two speakers of course.

[dime196604]

Maybe a dumb question here. Does the polarity of the headphones or speaker matter when you wire it up to this board? If so what would be the best way to figure out what pin is positive and negative on the board?

[dime196604]

The preamp is the first opamp the signal hits as it enters the board;

[ATTACH]36602[/ATTACH]

Thanks Bob

[FatBob]

The preamp is the first opamp the signal hits as it enters the board;

[dime196604]

May be a dumb question but what chip on the board is the preamp? I'm used to working on radios and old tube gear.

[dime196604]

That's what i needed to know for now. Thanks. I was try and post pics of the wave i get on my scope, so you guys can let me know if i am moving in the right direction.

[Koala]

Thanks, do i need to be detecting anything when adjusting the damping? Or just have the coil connected with the power on? Sorry about my grammar on the last post, i did it on my phone and not the computer. Can't see the whole post when doing it on my phone

No

Just power.

[dime196604]

Thanks, do i need to be detecting anything when adjusting the damping? Or just have the coil connected with the power on? Sorry about my grammar on the last post, i did it on my phone and not the computer. Can't see the whole post when doing it on my phone

[FatBob]

I would say the 400 ohm is the best. It is narrowest and does not rise going to the level part.

[dime196604]

Fatbob, what one of those four examples would be the waveform I'm looking for? I'm not very experienced with a scope. The only thing I have used my old analog scope for is adjusting modulation on my AM transmitters. so I am used to only look for a smooth wave.

[dime196604]

Thanks for the reply guys. I have a LC meter so I don't have to use the coil calculator. When adjusting the damping resistor, do I need to be detecting metal? Or do I just need power going to the coil? Also what kind of waveform would I be looking for? I have seem a few examples here on the forum, but I am not sure what waveforms are the ones I'm looking for. Again, thanks for the replies.

[FatBob]

Here's some pictures of a coil with different resistors. You want limited rise after the pulse.

Damping.zip

[Qiaozhi]

Anybody out there???????????
Now i am looking into adjusting the damping resistor. I have a scope but only one channel works. Is it possible to set the damping resistor with only one channel? If so how would i go about it? Also how would i go about setting it without a scope?I have read about doing it with a scope here on the forum, but none of them say how to do it with any detail.From reading on this forum i believe i have the Surf XX board. Anyone willing to help me with this?

Use an adjustable damping resistor tool:
10k pot in series with a 200R resistor, and a 2k resistor in parallel with both the pot and resistor. This will give you an adjustment range from 181R to 1672R.
Attach the one good channel of your oscilloscope to the output of the preamp, and adjust the pot until you achieve critical damping. Disconnect the adjustment tool and measure the final resistance. Replace with a fixed resistor that has the closest value.