<div dir="auto">Yep, there's a vibrant analog video synth community these days using that same old tech from back when. Eurorack even.<div dir="auto"><br></div><div dir="auto">LM6172 is a nice little dual opamp with something like 80mhz bandwidth IIRC. Theyre easy to use because it's fine w +-12V rails. The DIP version just went end of life a few weeks ago, SOIC package is still being produced. Just mind the datasheet, it likes a 1k feedback resistor.</div><div dir="auto"><br></div><div dir="auto">Here's a little summing mixer schematic maybe it'll be useful to you.</div><div dir="auto"><br></div><div dir="auto">2mhz is nbd, I wouldn't sweat it too much. We're a bunch of amateurs monkeying w 60-80mhz for vertical rate stuff and seems like most people's PCB's aren't laid out with any kind of understanding of signal integrity whatsoever and it all works just fine.</div><div dir="auto"><br></div><div dir="auto">Uninterrupted ground planes are your pal </div><div dir="auto"><br></div><div dir="auto">You could probably ask on LZX Community Forum if you run into snags, there's a handful of video DIYers there that kick schematics around and tend to be helpful. There's a discord as well </div><div dir="auto"><br></div><div dir="auto">Cheers,</div><div dir="auto">Jesse</div><div dir="auto"><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Sep 29, 2023, 5:16 AM Roman Sowa <<a href="mailto:modular@go2.pl">modular@go2.pl</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Come on, this is basicaly almost a DC signal, let's not overkill this!<br>
I especially liked as someone joked about doing it digitally in FPGA.<br>
<br>
In the old days of analog television, this was called "video bandwidth" <br>
and what comes wit it - huge variety of video opamps, with enough power, <br>
bandwidth and low distortion to use in such scenario. My prefered <br>
all-purpose models were AD818 and AD817, but that was 25 years ago. <br>
Nowadays there should be hundreds of better and cheaper opamps. Just <br>
build resistive adder like you would do for CV in modular synth, the <br>
only difference being resistor values to provide matched load impedance <br>
for individual transmitters. The opamp will provide enough gain and <br>
output power to drive antenna directly with those few miliwatts.<br>
<br>
Roman<br>
<br>
<br>
W dniu 2023-09-28 o 23:02, Jean-Pierre Desrochers pisze:<br>
> Here is what I'm trying to do as an experiment.<br>
> <br>
> I have 4 small AM transmitters transmitting at 600, 900, 1200 and 1600Khz.<br>
> At about 10mW of power each.<br>
> I was thinking about mixing the 4 frequencies as a single unit<br>
> that I could adjust the final output transmitted on a small antenna.<br>
> That's my idea so far..<br>
> <br>
> <br>
>> -----Message d'origine-----<br>
>> De : Synth-diy <<a href="mailto:synth-diy-bounces@synth-diy.org" target="_blank" rel="noreferrer">synth-diy-bounces@synth-diy.org</a>> De la part de Gordonjcp<br>
>> Envoyé : 28 septembre 2023 16:46<br>
>> À : <a href="mailto:synth-diy@synth-diy.org" target="_blank" rel="noreferrer">synth-diy@synth-diy.org</a><br>
>> Objet : Re: [sdiy] 4 channel mixer of signals with frequencies between<br>
> 2Mhz<br>
>> and lower.. any circuits available.. ??<br>
>><br>
>> On Thu, Sep 28, 2023 at 03:17:56PM -0400, Jean-Pierre Desrochers wrote:<br>
>>> Hi all,<br>
>>><br>
>>><br>
>>><br>
>>> This is an out off topics question but I will ask you anyway..<br>
>>><br>
>>><br>
>>><br>
>>> I want to build a 4 channel mixer that would receive signal<br>
>>> frequencies between 2Mhz and lower one channel..<br>
>>> These 4 frequencies won't change. They will be fixed.<br>
>>><br>
>>> Google would give me lots of Radio/Ham solutions that imply the use of<br>
>>> tuning coils and such things I don't want to get into.<br>
>>><br>
>>> The idea would be to use ready available opamps with high bandwidth<br>
>>> with the use of resistors and caps only. Gain would be of one.<br>
>><br>
>> For the avoidance of the XY Problem, what exactly are you trying to do?<br>
>><br>
>> --<br>
>> Gordonjcp<br>
>><br>
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