DC filter

[peranders]

I work with relays at work I even sell them, so horrible is a strong word. The relay, depending of design has hysteresis, more or less. Those with very little hysteresis, this kind of circuit is not very suitable but for a "normal" relay it will work rather OK but I prefer they way I have solved this problem.

 

[Elso Kwak]

Simple circuit

Hi,
Attached a very simple circuit that is working since 29 years with a 1k5 Watt transformer.....(NOT a toroid BTW!) Of course this is a AC relay.

 

[bremen nacht]

Sorry to use a strong word! The fact that wuffwaff's amp hasn't allowed the blue smoke to escape goes to show that it's a good 'un and that I'm maybe too quick to condemn something that doesn't look good on paper.

 

[Claus]

I have been using a circuit similar that from Elso for more than 12 years on my Futterman otl3e clones. Powering a 1000VA Toriod transformer up. I never had a blown fuse.
Simplicity at its best.

Claus

 

[wuffwaff]

I calculated 1.000uF for 200W maximum output @230V input [I tested a 750VA toroid but I had nothing at hand to dissipate more than 200W]. For higher power output it would be also a good idea to use diodes rated at a higher current than 1N4007 since they will have to pass all the load current in case of capacitor failure or excessive voltage swing

Hi Eva,

Just a question, did you calculate 200watts for two 1000uF caps back to back? How did you calculate this? I looked at average current, multiplicated by three and compared to the ripple current possible. This sort of fits but not exactly.

William

 

[Taffi]

Have been listening to DC and amp buzzing all night and had enough
Something has to be done NOW!
Found 4pcs Rifa PEH 169PO5100Q.
10.000uF, 100V laying around.
Is this enough to stop the DC or do I HAVE TO use diodes too?
As I have two different lines (balanced 230V as we have it in Norway and Albania) I wonder if these 4 caps would be enough for both lines?
And how should I connect them?
Are the polarty important?

 

[peranders]

How much capacitance you need is determined by the primary current and diodes are good as transient protection.

You have to put these caps i series and one wire is enough. I t has nothing to do with the absence of "neutral". If you as I or Lars Clausen have done it will work in 99% of the cases.

The caps you have got is extreme overkill (10 or 25 volt rating is needed) but will do a splendid job.

 

[Upupa Epops]

By my listening experiences with serial condenser, in this case little bit " die " dynamic, which is probably caused by auxiliary impedance of this circuit. Much more better solution is using of " overkill " insulating transformer, which must be located in other room, 'cos in this case is humming too . Very elegant solution have Dieter Burmester, but it is patented ( I forgot number of this patent ).

 

[Taffi]

You have to put these caps i series and one wire is enough. I t has nothing to do with the absence of "neutral". If you as I or Lars Clausen have done it will work in 99% of the cases.

If I use only one cap wouldn't it be possible that I still could get DC between the other phase and ground?

 

[peranders]

Remember that the primary winding has only two wires and it's enough to have some in series with one of them.

If you want inspiration you can check my filter or Lars Clausen's.

My and Lars' solution is at least much cheaper than Upupa's

 

[peranders]

Very elegant solution have Dieter Burmester, but it is patented ( I forgot number of this patent ).

At the Arken exhibition 2004 I have seen his gigantic box but it was empty because it was so heavy

http://hififorum.nu/forum/topic.asp?TOPIC_ID=34612
http://hififorum.nu/forum/topic.asp?TOPIC_ID=32464

 

[Upupa Epops]

To P-A : His " Mains washing machine " isn't so heavy , but is able to make DC unbalance of mains below +/- 1 mV .

 

[richie00boy]

Re: Simple circuit

Hi,
Attached a very simple circuit that is working since 29 years with a 1k5 Watt transformer.....(NOT a toroid BTW!) Of course this is a AC relay.

How is the delay determined with this circuit? Is the timing affected by all the components?

 

[peranders]

1 The voltage drop of the R (caused by the resistance and the inrush current).

2 The pull-in voltage of the relay.

 

[richie00boy]

Thanks, but what influence does the cap have? Surely that is what causes the delay.

 

[bremen nacht]

MAPLIN - my vote for the most incompetently managed company in the UK.

ha ha - bit harsh but I know what you mean. Their website is a mine of misinformation and the catalogue is hilarious '...a very proffesional pair of headphones frequency response 5Hz to 35KHz £9.99...'

 

[richie00boy]

That as well, but my comment is more directed by the fact that I have an understanding of what goes on inside the company. Joined-up thinking is something that company have yet to stumble across.

 

[maxlorenz]

Sorry to intrude.
The noisiest transformer in my (and I presume in everyone's) house is the refrigerator's one. Although I have dedicated power main for my system I still suspect this fellow for contaminating my music. Could a DC blocking filter be useful there?

Thanx

 

[GregD]

What about using an AC rated metalized polypropylene capacitor for DC blocking. Specifically, I'm looking at the Cornell Dublier SF series.
http://www.cornell-dubilier.com/catalogs/SF.pdf

It seems that this should do the job, handle lots of current, be relatively compact, and not require any bypass diodes for protection. Unless I'm missing something.

 

[peranders]

The noisiest transformer in my (and I presume in everyone's) house is the refrigerator's one.

.... you mean compressor....