Caiman Output Noise

[Reid Malenfant]

Ah, but you were listening carefully to this whining sound so you might have only just noticed them clicking off?

All you should get is a quiet click or as they are only small reed relays..

As you say, it's probably for the best if you aren't 100% sure of what you are doing to keep a standard one handy

You have a multimeter don't you, have you tried measuring the voltage into the Caiman to see if there is any AC content? It occured to me yesterday but i forgot to mention it

[chrism]

Hi Mark,

Think that I will wait and ask someone with some depth of knowledge on the subject aka Les W over at Avondale when he is back at work.

Thanks for your own thoughts though (yes I do know which end to hold the multimeter).

Regards

[andreime]

Post a pic, it might help more!

did you remove anything else than the cap?

[chrism]

Sorted it!

I swapped the Slimic out and put the big yellow polyester 10 microfarad back in and the whine has reduced to almost nothing. Could be RF not sure.

I am feeding 15.8v (without load) into the Caiman through my new Linear PS and checked the voltages under load at the Murata's. I measured 12.76v at the 12v Murata with 11.97v out. The voltage at the input cap is around 14.7v. Any one else checked this as I suspect that the 12v Murata may not see enough voltage drop through it.

Back to my main project which is to feed dedicated 12v and 5v supplies in and take out the Murata's without tears!

Mark, you made a comment about measuring AC but I really cannot get my head around what you have asked as all DC supplies will give an AC reading.

Regards

[MartinT]

Chris - are you really measuring 12.76V at the Murata's input? That's far too low for a 12V reg and it will have trouble doing any regulation at all. Where is the voltage being dropped? Is your PSU generating enough voltage under load?

[Reid Malenfant]

Mark, you made a comment about measuring AC but I really cannot get my head around what you have asked as all DC supplies will give an AC reading.

Regards

If a DC supply had infinite current supply, or if you like an output impedance of zero then there should be no AC voltage at the output terminals of the supply

Introduce any kind of resistance though & a varying load & you'll see AC voltage superimposed on the DC supply line. What i was interested in was how much AC voltage you are seeing superimposed on the DC supply at the Caiman input. In all honesty it shouldn't be a lot, but if it was then we might be getting closer to the problem

Multiple choices, measure different things & narrow it down is all i was trying to help with

[chrism]

Hi Martin,

Could you please check your Caiman and measure the 12v Murata voltage as I think you may have mentioned that you have set your PSU to 16v. I am interested in what you find.

Mark, could you please measure a DC supply for AC and tell me what you find. PS I think that you may be addicted to smilies!

Regards

[MartinT]

Chris - my power supply is set to exactly 16V and the voltage at the regulator input is about 15.4V due to the protection diode drop. The output is about 11.9V, perfect. I don't use a Murata, I use a Dexa but the principle remains - my regulator drops about 3.5V which is fine.

[Reid Malenfant]

Mark, could you please measure a DC supply for AC and tell me what you find. PS I think that you may be addicted to smilies!

Regards

Hi Chris, i'd love to but my Caiman is sat in a box

As for the smilies at least you get the point rather than misunderstanding the intended tone...

I'd expect your voltage readings to be similar to Martins -1V due to his 16V DC feed, they aren't so something is going on somewhere if you are feeding it 15V DC.

[chrism]

Thanks Martin, my PSU is set to 15.8v without load and I read a 0.7v reduction through the diode. I will have a look at the tracks in that area as I have noticed that the DC jack is a little wobbly. I also needed to replace the wiring between boards as it eventually got fed up of being twisted about. I will have another look here to see if a connection is poor.

Mark, all DC supplies will read AC also and I just wanted to make my point. I am really grateful for "useful" discussion about what could be wrong or worth looking at and glad to hear that you don't intend any put downs with smilies added to infuriate.

Regards