I’m thinking about getting a simple signal generator – preferably in the 50-100 MHz range – with multiple wave forms for modulating video signals. Are there any cheap ones you know of?
I’m open for DIY/kit suggestions, but I’d prefer just bying a ready made box with some BNC connectors ready to be plugged in.
Where do you source your MHz oscillators? - _ *
Jonas Bers CHA/V video synth is kinda of OG.
Great starting point to learn. He has an updated version 3.0:
but if you want to learn circuit bending electricity into light the first link is a good starting spot.
And if your interested in potentiometers Lo-Fi Future has a pretty easy build:
Lofi also has some gear you can buy since you’re interested in a ready made box.
Thanks. But by signal generator I mean a good old function generator, not a video synth. I already have a synth!
What do you consider as cheap?
I bought one of these and it’s really cheap. The internal reference clock is just a standard quartz oscillator but there are mods to put a more stable one inside. However it can only output a 60MHz sine wave. The arbitrary wave forms only go up to 6 Mhz. But if that is enough for your purpose it will work fine.
I don’t know of any cheap wave form generators that can output arbitrary wave forms up to 50 MHz. If someone knows any please post them here :))
im a fan of this ZEEWEII DSO154Pro 18Mhz - mainly for an entry level scope for inspecting video signals but i use the function generator on this all the time to test my video circuits.
wrote a bit about some entry level scopes here
from memory it goes up to around 1Mhz - has all the usual function generator waveforms (not arbitrary wave forms) - i like that it can go quite slow too - down to like 0.1hz - good for slow changing modulation… - i soldered a 3.5mm socket onto mine to use more easily with eurorack patch cables…
the output is fixed at 3v3pp tho - one thing that i miss from the other cheap function generators like FG-100 / FG-200 DDS is they have adjustable amplitude and dc offset which can be very useful… (otherwise the interface is trash tho) was thinking of adding a small opamp circuit to my ZEEWEII to achieve this same functionality…
I’m kinda interested in these cheapo function generators as well, do you know if they can be set to output 0-1v for eurorack video signals, or do you need to add something else (resistors, diodes, etc) to the output to make it “safe”?
Mainly asking since I’m thinking of building a recurBOY and Syntonie CVB002 in the future as a basic eurorack video setup, so if these basic functon generators can be used with them it might be worth picking one up to mess around with
The JDS6600 from Joy-IT is capable of outputting 0-1V. The handling is a little awkward though, because you have to keep track of the offset voltage and output swing in your head to not exceed those limits.
The second link that @cyberboy666 provided (FG-100 / FG-200 DDS) is also capable of setting the voltage swing and offset. It’s also a lot cheaper than the Joy-IT unit. I think for testing and playing around this one is more suited.
As for the hard limiting of the output swing my best guess is to use a simple diode clamping circuit. But then you have to generate a 1V clamping voltage rail.
Or you can try using a simple 1V Zener diode to limit the voltage.