Bode plot with Rigol DHO924s
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- เผยแพร่เมื่อ 4 ต.ค. 2024
- First try with a transformer and a simple filter. The transformer is there to protect the function generator. Generator sees a high impedance. The tested circuit sees a low impedance input over a small resistance added in his feedback loop. But here , this is only a simple filter at the output of the transformer. I will modify a switching power supply soon.
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Hello. I recently got the same oscilloscope and your videos are very instructive. Rigol recommends using a transformer to match the impedance between the generator output and the circuit to which the signal is sent. However, unless I'm mistaken, the datasheet gives no information on the electrical characteristics of the transformer to be used. I used the output of the generator without a transformer on a 455kHz ceramic rejection filter. Its input impedance is quite high, around 100kohms, and the Bode diagram was produced without any problems. I understand the use of the transformer in the typical switching power supply diagram provided by Rigol, but if a transformer is required to protect the generator output, Rigol should give the electrical characteristics of this output. Is it that fragile, and if so, what is it made of? Unless the electrical characteristics of this output are available, but I haven't found them. Thank you for your videos and best wishes for the future.
You want to protect the generator from high voltage and low impedance. I have tried a few transformer but they where limited in frequency. I have fond a very old 1970 transformer that was sealed and was amazing performer with first resonance at 260Khz with almost flat response up to 25Mhz! There is one now on eBay, search PCI 2012B 501-002. Don't rush to buy it and try instead what you have in hand...
@@stevelevesque939 Hi Steve. Thank you very much for your reply and for the suggested reference for the transformer. I'm not going to rush into buying such a transformer before looking at what I have in my drawers.
In my opinion, this transformer is not useful, for example, for measuring the bandwidth of filters based on operational amplifiers with a high or even very high input impedance.
As I'm not doing much development work or measurements on switching power supplies at the moment, I probably won't be using this type of transformer in the immediate future.
Nevertheless, it would have been nice if Rigol had given us the electrical characteristics of the output stage of the DDS generator built into the oscilloscope.
Also, thanks for the video posted yesterday on the use of this transformer and its frequency characteristics. I look forward to following you on TH-cam.
Hi Steve, I've read a lot of comments about bugs in the firmware of the DHO800/900 series. Would you still recommend buying this oscilloscope for fairly frequent use to generate bode diagrams and use mostly in linear electronics? If not, do you have any suggestions at a price of less than $1250 CAD? We look forward to hearing from you.
Hi , there is a new firmware that got out on Sept 5 that seems to resolve most of the issue that I have found. however it was removed due a new XY display bug. I expect it to be relaunch in few weeks, I will try it then. To get bode plot you need to go 914s or 924s. To me the bode plot works well in an integrated scope package. Alternative is Siglent sd8xx HD or SDS1104X-E however you need their external pricey function generator and software add-on to make it works. I didn't try it myself but some review says its better.
@@stevelevesque939 Thanks for the information, I'll take a look at this Siglent combination too. In the meantime I saw that there is the KeysightDSOX1204G, 70MHz available from Aliexp... for 1250$CD free shipping and the Bode plot is also integrated in this oscilloscope. It's 5 years old though, probably 8 bits and no touch screen. Is it a better alternative in your opinion?