Bypassing

When bypassing caps is it just a case of soldering the bypass cap to the pins of the cap to be bypassed? If that makes sense.

whats the general rule for values?

Many thanks.

 

Yes, the bypass can be put across the pins of the big cap.

As to values....

Some people reckon on using caps of about three orders of magnitude apart. So, if you have a 10000uF reservoir, bypass wit 10uF and bypass that with 10nF.

Otherwise you can take the approach that you're looking to improve HF performance where the inductance of a physically large cap hinders it. In which case you put the largest value smallest package cap in that you can. 1uF 0603 are something of a favourite at the moment.

 

Yep. Values I usually use about 1% so 100uF are bypassed with 1uF. Not sure theres any scientific basses to that, or even where I got it from but it works fine.

 

Hope this helps,
you solder the bypass cap directly across the main cap
you would normally use polyprops with the 1/100 rule ie. for a 100uf use a 1uf polyprop

David

 

Thanks for that. So for my 470uF caps Id go for 47uf and 47nf? and I solder these to the pins of the big cap? or would I solder the 47nF to the pins on the 47uF which is soldered to the pins on the 470uF?

 

It doesn't matter, as long as the leads of the bypass cap are accross the pins of the cap your bypassing, whether directly or somewhere else in the circuit it will still have the same effect

 

Just make sure to get the polarity correct if using polarised electrolytics.

 

Mr. T what are you going to bypass? To give a guidance it's necessary to know where this cap is located.

 

The psu caps in my valve power amp. Ive tried and tried to get replacement caps but I cant. Size is a major issue if I do replace them, I am limited especially in diam. What I do have is alot of space around them to lie caps horizontaly if needs be, so i thought it might be best to bypass whats there.

I'l probably do my valve pre too, but I seriously limited for space so it'll be Wima's in there.

 

No............ the bypass value is 10% in all the refferences I have ..Audio Convertions common ground etc.

I often build a vero bopard module to house a row of caps of decreasing value ie 10000,1000,100,10,1uf .The connections to th pcb being taken from the centre of the board rather than one to keep the conductor lengths as short as possible.

Also two small caps are better than one big on of the same cumulative value, three are better than two etc..........

 

I bypassed the power caps in my valve amp, immensley fiddly at times without serious stripping the amp. Im quite impressed, most notable increase is in the bass. A worthwhile upgrade.

 

I'd agree............I always try when modding any gear to do at least the power supply caps.

 

I quite like the idea that you posted above, Ive plenty of space (in valve amp terms) that I could use. Im not going to do it yet but ive some idea's brewing.