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| 2 opamp as bridge output. |
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| GigaJoe:
Hi everyone, so i got a thing beyond my knowledge , hope someone able to explain it , where is my mistake . I take dual opamp and feed 2x10V first non-inverting ; second opamp - inverting ; K=1 for both ; feed 20Khz meandr . that are result: A - no-inv, B -inv ( measure between ground (neutral) and output of each opamp ) Then, I measure output between both opams, (like a bridge) here is output between both opamp: I assumed that result would be a simple add on , as a flat meander (in fact amplitude doubled), then I able do feed 2 TDA opamps as the bridge. Why it not flat? and getting much worse when F increasing, like 60-70K it not even close to meander, some chaotic thingi . Where is my mistake ? |
| Zero999:
It seems like you're measuring it incorrectly. Have you got the oscilloscope ground on one of the outputs? If so, then this is the problem. Either use a differential probe, or two channels and the x-y maths function. |
| spec:
Hi GigaJoe We would need a full schematic, including the opamp type, and an indication of how your scope is connected to the circuit, before we could even start to help you. |
| GigaJoe:
Hero999, :-+ :-+ I'm :palm: :palm: :palm: :palm: Like a primitive error, in measurement , a ground has to be at ground. Otherwise it begin an antenna to accepting all here is a picture when I hold the ground cable ( short black path with crocodile) by fingers ... that a frequency comb produced |
| SiliconWizard:
Use a differential probe or show the difference using two probes and a math channel on your scope. Connect the scope's ground to your circuit ground and certainly not to any of the opamps output except if your circuit is completely isolated... You may also insert a load between the two outputs (if you haven't) as there will probably be one in the end if you're using this as a bridged amplifier and you need to check whether both opamps will be able to source and sink enough current. |
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