[USRP-users] LFTX Pk-Pk voltage

Marcus Müller marcus.mueller at ettus.com
Wed Apr 29 11:34:57 EDT 2015


In addition to what the other Marcus said, if you really want to make an
TTL impulse out of the signal, I'd try something like hooking up a
comparator between the center and either a reference voltage (zener
diode or just a voltage divider); the LM339 isn't really an investment
by itself, and I'm pretty optimistic that TI might give you a sample for
free, but basically any comparator should work (note that I wouldn't
trust this one over >1MHz). All these values are absolutely "Um, I just
came up with this, because that's what I'd have in my cabinet" (OK, R1
matches the source impedance, so you might want to stick with it, but
then again... this doesn't really matter). Add a feedback resistor
between Pin 1 and 3 if you want hysteresis; it depends a bit on your
signal and the comparator you use which resistance you'd want for that.
I'd start with 5 times R3. Notice that without any feedback, you might
see this thing go into oscillation if you just let its inputs float (or
just supply a DC voltage). So maybe I should have added that to the
schematic below. Oh well.
schematic


Best regards,
Marcus

On 04/29/2015 03:51 PM, Nemanja Savic via USRP-users wrote:
> Hello and thank you Marcus (and other guys),
>
> I should have taken a look on schematic. My idea was to drive external
> trigger of HAMEG programmable synthesizer, which accepts TTL level and
> it looks like I will have to change that feedback resistors.
>
> Best
>
> On Tue, Apr 28, 2015 at 7:15 PM, <mleech at ripnet.com
> <mailto:mleech at ripnet.com>> wrote:
>
>     In  my reply earlier, I said "ADC", when in fact I meant "DAC". 
>     The DAC still has a reference level, set by the DAC
>     hardware--thanks to Ian for politely and discretely pointing this
>     out :)
>
>      
>
>     Which means that output levels will vary somewhat among different
>     USRP "host" devices.
>
>      
>
>      
>
>      
>
>     On 2015-04-28 06:27, Nemanja Savic via USRP-users wrote:
>
>>     Hi all guys,
>>
>>     I wonder whether possible to drive LFTX output to more than 1V
>>     Pk-Pk, which is at the moment maximum that I can get.
>>
>>     Thanx,
>>
>>     -- 
>>     Nemanja Savić
>>
>>     _______________________________________________
>>     USRP-users mailing list
>>     USRP-users at lists.ettus.com <mailto:USRP-users at lists.ettus.com>
>>     http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
>
>
> -- 
> Nemanja Savić
>
>
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