| Electronics > Beginners |
| Low Freq. (below 1KHz) signal generator ? |
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| tautech:
--- Quote from: pilor001 on April 25, 2018, 10:51:27 am --- 8) Have been looking at this SDG 805 too. ... and the SDG 1025 Still.... a good question is that.... all the tests (youtube...) are always about the "how high" can we go.... So no real test at the low-low ranges. |O |O --- End quote --- All I have now is the more modern SDG1032X (30 MHz) but I'll put some screenshots up later and show the 'real' rise and fall times, however I can tell you now they'll meet and better the datasheet spec. A previous SDG1010 demo I had easily met spec and IIRC they were in the single digit ns range. |
| JohnPen:
The cheaper Feeeltech FY3200S will provide an output frequency down to 0.1 Hz in 0.1 Hz increments over your specified range (up to 5 Hz). The rise and fall times are under 40 nsec. |
| tautech:
A few screenshots of SDG1032X of squarewave and pulse at max amplitude into 50 \$\Omega\$ Scope SDS1202X-E Assorted screenshots. 100mHz 1Hz 10Hz 100Hz Measurements don't always give precise indication of rise/fall so there's a zoomed shot that shows the edge better. |
| pigrew:
The Siglent SDG2xxx's DDS implementation causes frequency errors at low frequencies. I put a table of errors in the SDG2xxx thread. IIRC, they become quite significant with frequencies less than 10 mHz or so. I don't know if other generators have this issue, but it is something to watch out for. If you want a square wave, you can add a comparator/buffer IC to make edges faster (with a phase noise penalty). Some generators even do this internally. However, for most DDS generators, the rise time is inversely proportional to the max rated bandwidth of the generator. |
| woodchips:
Look out for the Feedback function generators. The VPG608 does 0.01 to 1kHz The FG601 does 0.001 to 1MHz The SFG606 does 0.01 to 1MHz Some have sweep, variable phase etc. All good reliable analogue instruments. |
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