Hantek dso2d15 Noise from internal power supply - Page 1
Forum section: electronics / testgear

author: iw2evk
author_rank: Contributor
timestamp: September 23, 2024, 06:49:39 pm
content: Hi,somone have tried to modify internal circuit of dso2d15 for reduce the radiofrequency noise irradiated from scope?I've placed a ferrite sleve on main cord but it's not sufficent for reduce noise.All around the scope for about 1mt i've strong radio noise on wide spectrum frequencies.need help , pleaseRoberto iw2evk

author: Aldo22
author_rank: Super Contributor
timestamp: September 23, 2024, 07:32:43 pm
content: I think it's the screen, not the power supply.

author: iw2evk
author_rank: Contributor
timestamp: September 24, 2024, 06:19:59 am
content: Nothing to do ?use a shieded cable for carring out the signal far away to oscilloscope ?

author: Aldo22
author_rank: Super Contributor
timestamp: September 24, 2024, 09:07:07 am
content: Quote from: iw2evk on September 24, 2024, 06:19:59 amIf you want to shield it for the other devices, a Faraday cage may help.If you simply want to see less noise, you can try the following:- Use a direct, short BNC connection to the DUT whenever possible.- If you use the probes, use the 1x mode (for the smallest signals anyway).The less stuff hanging on the probe (sprung hook, alligator clip) the less “antenna” you have.- Turn on the bandwidth limiter (BW 20M).- If it does not trigger cleanly, a trigger holdoff can help (perhaps via PC).- For repetitive signals, the "Average" acq. mode can help (or a little less the HR mode, for any signal type).Noise is everywhere. Maybe it's not just coming from the scope?I don't think the noise is that bad if you help a little.In the attached image you can see a measurement with- Probe (1x), sprung hook and alligator clip (i.e. completely normal).- BW limitation on- Average Acq. (8x).This is a very small signal for a measurement with the probes (6.5mVpp) and it still looks reasonable to me.

author: Aldo22
author_rank: Super Contributor
timestamp: September 24, 2024, 09:47:18 am
content: And before you curse the DSO2000:It has pretty good sensitivity for such a cheap scope.With a FNIRSI 1014D or 1013D you would see as much as in the attached picture of the signal above (50mV/div).In this case the noise is not an issue.

author: iw2evk
author_rank: Contributor
timestamp: September 25, 2024, 11:41:55 am
content: Hi,i've order a double shelded 50 ohm bnc to bnc 1mt cable.So i suppose can take awey the DUT from scope and reduce noise.P.s. my test are on radio device, so i suppose i due buy a 50 ohm attenuator for reduce the signal from internal scope generator to input of radio..Or i can make the attenuator with a kit ?

author: Aldo22
author_rank: Super Contributor
timestamp: September 25, 2024, 01:17:06 pm
content: Quote from: iw2evk on September 25, 2024, 11:41:55 amI'm not sure if that's a good idea. Maybe you pick up even more noise this way, because the cable is longer?Can you show a picture/screenshot of what it looks like in your case?When I place the probe directly on the scope/screen (picture 1), I see a lot of noise.But in normal operation (picture 2) I don't think the noise is excessive.The setting in the pictures is: probe 10x, without BW limitation, with HR mode and persistence 1s (100us, 20mV/div).https://youtu.be/sWPRAKayC3g

author: Maximplus
author_rank: Newbie
timestamp: September 25, 2024, 08:20:50 pm
content: Many people note that this oscilloscope has a primitive and noisy power supply. Its replacement or additional screening with filtration should help significantly. Unfortunately, the source is 2-channel, there are 5 and 12 V, inconvenient to replace. There is a lot of information on the redesign on youtube, including a video where a classic power supply with linear stabilization was used. Without pulse conversion.

author: iw2evk
author_rank: Contributor
timestamp: September 27, 2024, 06:18:27 am
content: Mhh..can i add some ferrite bead on internal cable and/or ceramic capacitors on pcb of voltage regolator output ?I don't have found imeges on web..

author: croma641
author_rank: Regular Contributor
timestamp: September 29, 2024, 12:28:31 am
content: Found this..This one: exaggerated:For thermal problems:'73

author: iw2evk
author_rank: Contributor
timestamp: September 29, 2024, 07:15:44 am
content: Ok,i've see the video.2 video for add a heathsink to 2 ic (can reduce noise? i don't think this, maybe work more safetly the ic with less heat )1 video for create a mains insulation with 2 transformer in cascade (mhh.. this can reduce noise from mains, not the producted from internal circuitery)no video explain if it's possible place ceramic capacitors for drain to groud rf from +5 , +3,3v etc ..I see in the video 2 flat cable near the switching power suplly . some ferrite rings on this cables maybe a solution ?

author: Aldo22
author_rank: Super Contributor
timestamp: September 29, 2024, 05:39:44 pm
content: I had a look at this with the TinySA.From my point of view, most of the radiation comes from the screen.In the first picture, the antenna is directly on the LCD.In the second picture, the antenna is directly at the back of the housing, where the unshielded PSU “radiates”. But that is significantly less.Then two more measurements at a distance of 40cm (front/rear).I don't know if you can do much about it.Much has already been discussed.78 pages here:https://www.eevblog.com/forum/testgear/new-hantek-dso2x1x-models/and 273 pages here:https://4pda.to/forum/index.php?showtopic=1018961

author: nokin
author_rank: Regular Contributor
timestamp: September 30, 2024, 06:49:42 am
content: Long time to come back to Hantek related topicMy experience for this Hantek model are :1. Noise and noise, lots of noise, no matter how hard you try to improve by any way. It is hardware related due to cheap model.2. Laggy and laggySo, change to another brand. Siglent or Rigol. They are more expensive but much better.

author: iw2evk
author_rank: Contributor
timestamp: October 07, 2024, 11:39:24 am
content: this is my lasr attempt to solve problem:1 ) ferrite sleve on main cord as a possible closer to female plug2) ferrite sleve on 2 cable departeing from switching to others parts cloer as a possible to pcbNothing again.. the noise decease but not disappear.Maybe place a copper foil over the switching (with insulation v.s. components )?the fundamental of swithcing seem about 40 khz , read on scope and received with radio..