Schematic for RTL-SDR V3

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jom
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Joined: Wed Mar 21, 2018 9:37 pm

Schematic for RTL-SDR V3

Post by jom » Wed Mar 21, 2018 9:42 pm

Hello...new here.

I just wondered if there was a schematic available for the RTL-SDR V3 module. I just bought one from Amazon (with the antennas and extras) and was curious. I can't seem to find anything on the website.

Thanks

jom

rtlsdrblog
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Re: Schematic for RTL-SDR V3

Post by rtlsdrblog » Thu Mar 22, 2018 1:07 am

Sorry our factory doesn't allow it to be released as their afraid of it being copied.

However there are some reverse engineered schematics for the generic dongles available here http://ggtoshi.at.webry.info/201406/article_6.html.

jom
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Joined: Wed Mar 21, 2018 9:37 pm

Re: Schematic for RTL-SDR V3

Post by jom » Thu Mar 22, 2018 2:27 am

Thanks!

That doesn't look like the V3 version...or do you know otherwise?

I was concerned about the new "built-in" Bias Tee function...I wanted to take a look to see how it's done. Ultimately I wanted to modify an LNA board I already have to see how I can use the RTL Bias Tee to power it. I also wanted to know what amount of current it could drive thru the Bias.

Thanks

jom

rtlsdrblog
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Re: Schematic for RTL-SDR V3

Post by rtlsdrblog » Thu Mar 22, 2018 5:54 am

Take a look at the feature datasheet https://www.rtl-sdr.com/wp-content/uplo ... asheet.pdf

It's 4.5V out and can handle up to 180mA. The bias tee is activated in software, see www.rtl-sdr.com/V3.

Basically the implementation is just an LDO with EN pin connected to a GPIO on the RTL2832U. Turn that GPIO on and the LDO turns on. The bias tee part is just a high SRF inductor and blocking cap.

W1ABA
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Re: Schematic for RTL-SDR V3

Post by W1ABA » Fri Jul 06, 2018 7:14 pm

Warning, [OT] follows.........

Hey rtlsdr blog,

How about controlling the heat inside the RTL-SDR housing by moving the voltage regulators off the motherboard? While switching regulators are a step in the right direction, they create rf noise. RF noise that likely insures the antenna input is overloaded. Can we get some support from the company with regard to mods to move the switching regulators off the motherboard?

Put the RTL-SDR in a screened enclosure, it will improve the units ability to dissipate heat. While the chips themselves use lots of power, an improved heat management system should greatly improve.

While you might not be able to disclose technical information about the chips used, surely technical information with regards to the electronics your company designed and built (such as the power supplies) can't be off limits.

Any information is helpful.

And, thanks to you and your company for sponsoring the forum-it's a fantastic resource.

1ABA

rtlsdrblog
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Re: Schematic for RTL-SDR V3

Post by rtlsdrblog » Sun Jul 08, 2018 11:27 am

The voltage regulators actually don't produce the majority of the heat, most of it comes from the R820T2.

With the metal case on the V3 acting as a heatsink, all the previous L-band VCO heat related lock problems are eliminated. The case can feel hot to the touch in warm ambient environments, but it's still enough to prevent lock problems.

BTW, the V3 uses a low noise LDO, not a switching reg.

W1ABA
Posts: 21
Joined: Fri Jul 06, 2018 5:05 pm

Re: Schematic for RTL-SDR V3

Post by W1ABA » Sun Jul 08, 2018 11:04 pm

I believe 5v and 3.3 volts are needed, and I thought I saw power conversion inductors on the PCB-so I assumed that those inductors were attached to switching supplies.

And, I thought I heard some chatter about the need to relocate them in order to improve the receivers sensitivity?

Perhaps I was mistaken-believe me, it happens.

Enjoy.

BB

rtlsdrblog
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Re: Schematic for RTL-SDR V3

Post by rtlsdrblog » Mon Jul 09, 2018 11:03 am

On the board there's a 3.3V LDO right at the input, and a 1.2V switching reg built into the RTL2832U chip. Some cheaper designs use a 3.3V switching reg instead, and they're usually very noisy. Of course those also have lower power usage, so it's a trade off. The built in 1.2V switching reg isn't particularly noisy, so it's kept there in our design to keep the current usage down.

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