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Help On Identification Of Capacitors

R

richard_crl032

Member
Hi All,

Newbie here and hope for some help on my vintage car amplifier before I work on some recapping effort. I am not an EE and do have some trouble understanding the various electronic terminologies.

Can some someone explain what are the various capacitors w.r.t. the common terminology on of input/output capacitors, coupling/decoupling capacitors, feedback capacitors etc. see in various recapping threads as show in the below? Thanks

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BTW, this car amplifier is 4 channels topology, zero feedback and bridgeable to 2 channels.
 
Hi sq225917, thanks for the advice but I do not have any other information/documentation other than the actual amplifier. I was hoping from the PCBA layout and position of the capacitors that someone can identify which are the power related capacitors and which are the signal related capacitor and if they are probably use as coupling, decoupling, by-pass etc. The 10uF 16 NP, 100uF 10V, 10UF 16V capacitors are certainly for input signal since it is near to the RCA outputs but do they function as by-pass, coupling, decoupling etc. ??

Thanks again.

Richard
 
"input capacitors" are in series (in line) with the input signal path and act to block any DC voltage that might come into the amplifier from preceding equipment also help set the low frequency response end of the amplifier in combination with a suitable resistor in parallel with (across) the input signal path.

"Decoupling capacitors" are in parallel (across) the power rails (ie between +V and ground and -V and ground) and smooth out power supply variation and reduce noise

"Feedback capacitors" are used to control the stability of the amplifier and set the low frequency end of the response.

Difficult to guess accurately which is which in the photo of your circuit.
 
Hi Engels,

Thanks for the definition of some of the terminologies which is certainly useful.

However, I am seeing at least 2 types of capacitors near the input power (22uf/25V, 680uF/25V), 2 types of capacitors (470uf/35V, 47uf/50V) after the DC-DC convertor if I under the link correctly, 2 types of capacitors (47uf/50V, 10uF/16V) at the output signal connecting wires and 2 types of capacitor at input signal (10uf/16V NP, 100uf/10V) which I thought can give some clues for at least guessing as to what functionality of these are.

For example the 10uF/16V NP should be decoupling caps for input signal and the 22uF/25V must be decoupling caps for the input power right??

Thanks.

Richard
 
Engels said:
"input capacitors" are in series (in line) with the input signal path and act to block any DC voltage that might come into the amplifier from preceding equipment also help set the low frequency response end of the amplifier in combination with a suitable resistor in parallel with (across) the input signal path.

"Decoupling capacitors" are in parallel (across) the power rails (ie between +V and ground and -V and ground) and smooth out power supply variation and reduce noise

"Feedback capacitors" are used to control the stability of the amplifier and set the low frequency end of the response.
Click to expand...

This is helpful (to me at least). So what are "coupling" capacitors?
 
Hi Stackowax,

Certainly not confirmed and hence my request for help but I believe coupling capacitor is what Engel advised on the the "input capacitor" i.e. in series (in line) with the input signal path and act to block any DC voltage that might come into the amplifier from preceding equipment also help set the low frequency response end of the amplifier in combination with a suitable resistor in parallel with (across) the input signal path.

From other sites, I can only speculate that both input and output signal as well as power input may have both coupling and decoupling capacitors but we can only speculate since there is not much interest in this thread which I thought should also be helpful for other newbies.

Cheers,

Richard
 
Sorry if I confused more than enlightened

"Coupling caps" - are indeed the series type. They connect (or "couple") the signal path in the different stages of the circuit togther. Often you would expect to find non-polarised (NP) caps used in this application, but thats not always true or necessary.

As opposed to "decoupling caps " - parallel type - which attempt to minimise the effect of any power disturbance on the signal circuitry ("decouple it from the PSU") Larger values of capacitance (bigger uF number) would be most likely for this application eg the 680uF and 470uF you mention.
 
Hi Again,

Can someone help to look at the link to the PCB layout of my car amplifier and advise specificiallyl what are each type of capacitors could be for.

Thanks.

Richard
 
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