Registration Notice

Due to increased spam, forum registration must be manually approved by a moderator! Please see this post for instructions.

*

Offline Rad_Schuhart

  • 99
    • View Profile
  • Graz, Austria.
Wiring an amp to the OP soundcard.
« on: September 17, 2019, 11:15:41 AM »
EDIT: I ended destroying my soundcard. I don't recommend to try it to anybody, not with the Open Panzer soundcard, and not with the Benedini Mini. If you, unlike me, know what you are doing and decide to try it, do it on your own risk. If it works, please post it so we can follow your steps. If it does not, please post it too for knowing what to not to do. Time to cry for me  :'(

Hi Luke, as I mentioned somewhere, when driving at the backyard and rising the volume, the speaker cracks quite a lot. I guess this is due to the lack of power, so I am planning to wire an amp to the soundcard.

I dont know how many W is your card able to pull, but do you think I can wire one of this to the board? https://www.aliexpress.com/item/32850211478.html?spm=a2g0o.productlist.0.0.6a3ca40dTGQrVk&algo_pvid=b1b999d1-3ff8-4b51-9e7a-6b711e1d2a6b&algo_expid=b1b999d1-3ff8-4b51-9e7a-6b711e1d2a6b-36&btsid=41910177-2c7a-4026-a6b0-098478ef8206&ws_ab_test=searchweb0_0,searchweb201602_4,searchweb201603_52

I am using them in benedini micros and they work like a charm.
« Last Edit: October 09, 2019, 04:03:42 AM by Rad_Schuhart »

*

Offline LukeZ

  • 817
    • View Profile
  • Kansas, USA
Re: Wiring an amp to the OP soundcard.
« Reply #1 on: September 17, 2019, 01:49:13 PM »
I have a hard time remembering but I think you have a Version 1 board with the 2.6 watt amplifier. That one does have a pre-amp output and yes you can try to connect it to an external amp such as the one you linked. I have tried those cheap Chinese ones including a variant of the one you linked to and found them to have a lot of distortion. It is also only 3 watts so not much different than 2.6 watts. But it is cheap enough that it doesn't hurt to try it.

The version 2 hardware which I think you don't have uses a 10 watt amplifier so volume is much higher. However it does not have a pre-amp output.
NO SUPPORT THROUGH PM - Read why
Need a forum account? Read here
Open Panzer FAQs

*

Offline Rad_Schuhart

  • 99
    • View Profile
  • Graz, Austria.
Re: Wiring an amp to the OP soundcard.
« Reply #2 on: September 17, 2019, 02:37:34 PM »
Yep, I have the 1.0 version. I'll try to find another amp at aliexpress tomorrow with a bigger output. A 5w one will be probably enough, but a 10w won't hurt neither.

Anyway It will be good for the science and also for editing my blog's entry!


*

Offline Rad_Schuhart

  • 99
    • View Profile
  • Graz, Austria.
Re: Wiring an amp to the OP soundcard.
« Reply #4 on: October 07, 2019, 11:23:49 AM »
Hi Luke,

I have received this today.

https://www.aliexpress.com/item/32861768239.html?spm=a2g0s.9042311.0.0.27424c4dTutOAh

I am specialist in making smoke with the electronics, and I want to prevent that. I think I know what to do, but can you offer me some guidance?

Thanks!

*

Offline LukeZ

  • 817
    • View Profile
  • Kansas, USA
Re: Wiring an amp to the OP soundcard.
« Reply #5 on: October 07, 2019, 01:27:59 PM »
Rad I'm assuming you're using the hardware version 1 of the OP Sound card, which has amplifier outputs.

Just connect the +/- from the Line Out on the OP Sound card to the input on the amplifier you bought. Output on the amplifier is obviously to your speaker. The amp also appears to need a 5 volt power source, which the sound card doesn't really have a convenient way of providing. You can use an external BEC or if you are using the TCB you can pull 5 volts from any number of places off of it, the I2C connector on the TCB is unused and it has 5 volt and ground connections.
NO SUPPORT THROUGH PM - Read why
Need a forum account? Read here
Open Panzer FAQs

*

Offline Rad_Schuhart

  • 99
    • View Profile
  • Graz, Austria.
Re: Wiring an amp to the OP soundcard.
« Reply #6 on: October 07, 2019, 02:36:32 PM »
Yep, I have the version 1.0

Cool, thanks! That is what I thought, except the 5v source. I was planning to use some sort of step down from the battery voltage, but now it has no sense if I can connect it to the I2c port.

I will try to do it this weekend, and if it works and I will update when it works.

I am sure this will make the speaker work much better.

Cant wait!

*

Offline LukeZ

  • 817
    • View Profile
  • Kansas, USA
Re: Wiring an amp to the OP soundcard.
« Reply #7 on: October 07, 2019, 03:30:31 PM »
Yes let us know, I will be interested to hear how/if it works.
NO SUPPORT THROUGH PM - Read why
Need a forum account? Read here
Open Panzer FAQs

*

Offline Rad_Schuhart

  • 99
    • View Profile
  • Graz, Austria.
Re: Wiring an amp to the OP soundcard.
« Reply #8 on: October 08, 2019, 02:42:36 PM »
Ok, I could not wait until the weekend, so I tried it and I have some horrible news here.

I wired the AMP following your instructions. My soundcard was indeed the Version 1.0 with the line out outputs. I soldered two pins there.
Then I checked the conection one zillion times:
+5, connected it to +5 in the IC2
gnd to gnd
IN+ and IN- to the OP soundcard.
And then OUT+ and OUT- to the speaker.
Before switching it on, I zillion checked it several times.

Then I switched it on, and I had a horrible noise comming from the speaker. Like a fast and loud pulse, but nothing else.

I switched it off and I checked several times I connected everything well. Switched it on again, and same problem.

I tried with a fresh battery, same problem.

Then I decided to, instead of using the +5v and -5v from the I2c, to try an external source of power. I used my voltage regulator, adjusted to 4.8v and then connected it in the +5 and gnd.

I switched the tank on, and hell, it worked. Volume was horrible loud and I could not adjust it. I switched it off and on again, and same problem with the volume. I switched it a third time, and suddenly silence...

I thought I blew the tamiya speaker, so I tried with several speakers I had at home, and no one of them worked. I also tried the King Tiger speaker with other electronics and still worked...

I took the amp away, and connected the speaker to the soundcard, and if I literally put my ear over the speaker I can hear small whispers when triggering the functions... So I guess I blew somehow the soundcard to my horror and despair.

Is there any way I can repair it?

Or even better, is any manufacturer going to produce it in the near future?  :'(

*

Offline LukeZ

  • 817
    • View Profile
  • Kansas, USA
Re: Wiring an amp to the OP soundcard.
« Reply #9 on: October 08, 2019, 09:30:29 PM »
Hi Rad, although I haven't fried anything your experience with the 22 cent Chinese amp is similar to mine - horrible sound quality. Electrical interference is always a problem, even on a properly-designed board with very careful trace layout the challenge remains, once you start adding external wires and such the problems only compound.

I'm sure you had the wiring correct but it would appear that the input impedance (or some other fancy-sounding word) of the Chinese amp was not compatible with the output of the OP Sound Card. This is probably why Benedini posts all kinds of cautions and warnings when using external amplifiers with his device. As mentioned in a different thread I have tried a few different cheap Chinese amps and haven't fried anything, but neither has the sound been any better. I have not done extensive testing of the line-out capability and you'll notice I removed it on subsequent revisions of the sound card.

The question here is whether you actually fried the Teensy, since the onboard amplifier chip is bypassed when using the line out. If so, you could buy a new Teensy 3.2 and just swap it out since it's on a socket, and most likely that will restore the functionality. You can buy one directly from PJRC in the States but I'm sure there are some EU sellers that have them too, for example it appears the Mouser EU has them. I would try that first and see if it fixes it.

As for the sound card entering production there is nothing in the works at the moment. If there ever is to be any future Open Panzer production I don't expect it to happen until late 2020 at the earliest. Even then that is a long way off and I can't predict if it will come to fruition or not. .

NO SUPPORT THROUGH PM - Read why
Need a forum account? Read here
Open Panzer FAQs

*

Offline Rad_Schuhart

  • 99
    • View Profile
  • Graz, Austria.
Re: Wiring an amp to the OP soundcard.
« Reply #10 on: October 09, 2019, 02:14:29 AM »
This is probably why Benedini posts all kinds of cautions and warnings when using external amplifiers with his device.

True. I always wondered why all the warnings... Now we know. Live an learn...

Do you know if there is a part of the teensy board that can be replaced? Maybe the teensy amp (if it exist) or something?

I am not the most skilled soldering guy, but I can try replacing some SMD components. Not a lot to lose because the board is already dead... After a visual inspection nothing seemed to be dead, but hey...

Anyway I will test the board again today. Maybe it was overheated or something, and it might work later on.

Yep, I know I am a dreamer.

EDIT: Quick question, a Teensy 3.1 will work, or the 3.2 is a must?
EDIT 2.0: The board is dead. I tried to connect it to the computer and not even that works. Sigh...
« Last Edit: October 09, 2019, 10:57:51 AM by Rad_Schuhart »

*

Offline LukeZ

  • 817
    • View Profile
  • Kansas, USA
Re: Wiring an amp to the OP soundcard.
« Reply #11 on: October 09, 2019, 03:47:33 PM »
There are really no user-replaceable components on the Teensy board. It doesn't have an amplifier on it, most likely what was fried was the DAC output on the processor ("digital-to-analog converter," which it uses to create sound waveforms).

Possibly that is the only portion of the processor that was damaged, but even if so it would render the sound card fairly useless. Your further test where it fails to connect to the computer would seem to indicate that the processor is basically dead.

For this application the Teensy 3.2 is required, a 3.1 will not work.
NO SUPPORT THROUGH PM - Read why
Need a forum account? Read here
Open Panzer FAQs

*

Offline Rad_Schuhart

  • 99
    • View Profile
  • Graz, Austria.
Re: Wiring an amp to the OP soundcard.
« Reply #12 on: October 10, 2019, 02:12:46 AM »
Ok, lets start the search of a new teensy 3.2

The chinese seem to have everything, and free shipping!:
https://www.aliexpress.com/item/33053619319.html?spm=a2g0o.cart.0.0.2f223c00REH7tx&mp=1

What do you think? Yes, I will miss the purple color, but if it works...

Also, once I buy it, and once I put the pins on it, what do I do? Do I just connect it to the computer and with the open panzer software do I flash the latest soundcard software?

*

Offline LukeZ

  • 817
    • View Profile
  • Kansas, USA
Re: Wiring an amp to the OP soundcard.
« Reply #13 on: October 10, 2019, 11:49:22 AM »
I would not suggest buying a counterfeit Teensy from China, there are many reports that they do not work. It also doesn't seem like they cost much less, and there is a good possibility you will just be throwing money away.

For the second part you are correct - just plug it into your computer and flash the Open Panzer Sound Card firmware using OP Config, that's all you need to do.
NO SUPPORT THROUGH PM - Read why
Need a forum account? Read here
Open Panzer FAQs

*

Offline Rad_Schuhart

  • 99
    • View Profile
  • Graz, Austria.
Re: Wiring an amp to the OP soundcard.
« Reply #14 on: October 10, 2019, 12:31:32 PM »
I would not suggest buying a counterfeit Teensy from China, there are many reports that they do not work. It also doesn't seem like they cost much less, and there is a good possibility you will just be throwing money away.

For the second part you are correct - just plug it into your computer and flash the Open Panzer Sound Card firmware using OP Config, that's all you need to do.

My godness, that's why is always better to ask. Thanks for the tip.

I sourced a german ebay seller, with affordable price and cheap shipping (3 euros)

https://www.ebay.at/itm/PJRC-Teensy-3-2-USB-Development-Board-32-Bit-ARM-72-MHz-Cortex-M4-IOT-TS01001/273030654757?hash=item3f91e52b25:g:Bi0AAOSw0gVdlyYA#shpCntId

Please take a look and tell me what you think. Anyway I am covered with paypal, so in case this is a fake version I can always claim or return it.