Sonda diferentiala

[VAX]

N-am desfiintat nimic, dar v-am dat alte idei. Nu am nevoie de pomana, am zis si eu la misto. Stiu si singur sa-mi fac sonda diferentiala. Mai greu mi-ar fi cu cablajul si deocamdata nu vreau sa stric unul din cele doua CLC425 pe care le am. Au zgomot foarte mic si sunt bune si la alte chestii. Am sa pun o schema de sonda diferentiala simpla, proiectata de mine, cu un singur AO si intrari pe tranzistoare, pentru cine va dori sa experimenteze. Peste cateva zile.

 

La joasa frecventa sa experimentati cu ROB74, varianta romaneasca (ICCE) a batranului uA740. Mi-e mi-a mers bine la cativa KHz. LM101A nu este bun de asa ceva. Puteti incerca si cu TL081. Pentru reglare CMRR montajul era prevazut cu un potentiometru (in locul uneia din cele 4 rezistoare - cea legata la masa). Aplicam semnal comun (sinusoida 100mV-1V vv) pe cele doua intrari si cu acel rezistor urmaream pe osciloscop sa reduc la zero semnalul de la iesire. Sinusioda disparea si se vedea slab armonica a doua, de la neliniaritatile din AO. Cred ca si la sonda pentru osciloscop trebuie sa se prevada un astfel de reglaj.

Editat Noiembrie 28, 2016 de VAX

[Ovidanie]

Sapphire SI9000 pe pagina a doua.

http://www.eevblog.com/forum/projects/high-voltage-differential-probe-design-for-review/

 

Ceva usurel, pentru laptop:

http://wiki.laptop.org/go/Measure/Projects/Oscilloscope_probe

 

http://en.elektronicastynus.be/projects/7/

 

[Ovidanie]

https://drive.google.com/open?id=0B1_1PbYW8joSdEdwODVxcXhJTXM

[cristi7521]

Ceva profesional dar vechi pt 1MHz

http://bama.edebris.com/download/tek/5a20n/5A20N%20Delta%20Amp.%20-%20Maintenance%20&%20Calibration%20Manual.pdf

[bogdanc2011]

Ce s-a intamplat cu proiectul? L-ati abandonat?

[sesebe]

Oarecum.........

Nu am resusit sa obtin in simulari performantele dorite, mai precis variaza foarte mult performantele in functie de elementele parazite luate in considerare.

O alta problema o constituie necesitatea unui cablaj pe 4 straturiceea ce iarasi este critic de obtinut pt ca la producatorii ciainezi nu prea ai date despre tehnologia si paramerii de inalta frecventa la cablajele lor.

 

Nu-i abandonat definitiv dar cine stie cind mai apuc sa butonez la el.

[cristi7521]

https://www.eevblog.com/forum/testgear/ininiimax-7ghz-active-differential-probe-teardown/

 

[sesebe]

Merci! 

Frumoase poze............

[cristi7521]

Diverse scheme:

http://1.droppdf.com/files/eDSD4/everyday-practical-electronics-september-2015-uk.pdf
http://blog.weinigel.se/2016/02/26/ghz-differential-probe.html
https://www.mikrocontroller.net/topic/382504
http://stevenmerrifield.com/diff-probe/index.html
https://www.diyaudio.com/forums/equipment-and-tools/248505-differential-probe-reverese-engineered.html
https://repozitorij.uni-lj.si/IzpisGradiva.php?id=72349&lang=eng&prip=rul:9166021:r4
http://land-boards.com/blwiki/index.php?title=DiffProbe
https://www.eevblog.com/forum/testgear/tek-p5205-hv-differeantial-probe-teardown-btw-what-are-the-red-and-brown-wires/50/        post 59 schema tek p5205
https://biblio.ugent.be/publication/4366182/file/4366199.pdf

[cristi7521]

Intre timp a aparut si o varianta testata/functionala si documentata de sonda diferentiala cu banda de aproximativ 100MHz.

Autorul a pus la dispozitie schema si fisierele gerber.

 

a 1Vp-p signal riding on a 230VAC mains line:

 

The Specifications:
Input impedance: 20MegΩ// 1.25pF - differential, 10MegΩ//2.5pF each terminal to GND.
Differential Gain = 1/10 V/V. Any lower than this and the DS1102E could not resolve a 1V signal with any clarity. (Many of the cheaper differential probes are switchable between 50X and 500X attenuation. This would be good if the signals in which you are interested are very large, but that's not the case so far with my needs. The better probes ($400 and up) provide 10X/100X attenuation.
Common Mode Range > ±340V (240VAC produces a sine wave 679V peak-peak)
CMRR >90dB @ DC, ~60dB @ 1MHz
Differential Voltage Range > ±24V for 240VAC common-mode,  ±24V for 0V common-mode (Paul's version increases both ranges to ±25V)
Bandwidth ≥ 100MHz (Dependent upon signal amplitude) This will be a stretch for my current skill set.
DC offset < 20mV
Noise: TBD (Wider bandwidth = more noise)
Cost: ~ $50

 

https://hackaday.io/project/169390-a-10x-100mhz-differential-probe/details

http://www.paulvdiyblogs.net/2017/10/differential-amplifier-probe-make-buy.html

[sesebe]

Impresionant CMRR de 60dB la 1Mhz dar am mari dubii ca este si verificabil prin teste la o schema co o compensare asa de simpla.