Bert,
Ok but how about Vellemans property that it connects relay back on after delay. If there is DC at output, i think it is not good to do that before DC is removed?
Maybe stupid question but i see it also has "commond ground" connection. Can it cause ground loop etc. problems with UCD?
Ok but how about Vellemans property that it connects relay back on after delay. If there is DC at output, i think it is not good to do that before DC is removed?
Maybe stupid question but i see it also has "commond ground" connection. Can it cause ground loop etc. problems with UCD?
Padi, it won't switch on if there is still offset. Don't worry, it will switch on when offset is lower than 1V.
I use a similar(20year old design) protection device with my UCD's and I find them extremely reliabe as they are fast with switching off and on. BUT you have to use powerline fuses for best protection. Use F4A fuses in the + and - line. Than you have a super stable protection system. This is for the UCD180.
Just looked at the diagram and this unit is fit for the UCD's. No problem. Just connect the 0V of the protection PCB to your earthpoint/0V in your cabinet. Easy as.....(not Dell)always
.
I use a similar(20year old design) protection device with my UCD's and I find them extremely reliabe as they are fast with switching off and on. BUT you have to use powerline fuses for best protection. Use F4A fuses in the + and - line. Than you have a super stable protection system. This is for the UCD180.
Just looked at the diagram and this unit is fit for the UCD's. No problem. Just connect the 0V of the protection PCB to your earthpoint/0V in your cabinet. Easy as.....(not Dell)always
.
Thank you Bert. It looks good setup then.
Why we still need fuses in ps. output, because UCD has overcurrent protection?
Why we still need fuses in ps. output, because UCD has overcurrent protection?
When the 2 output fets break/shortcut.......................BAMxxxxxxxxx............fire?
You absolutely need the 2 fuses to work together with the relay for maximum protection of your speakers. Please do it, you will never regret it.
its the combination of line fuses and relay that makes it such a safe protection system. But keep the mains fuse also. Better safe than sorry.😉
Bert,
I agree.
One more thing about Velleman K4700. It includes transformer and in my case i have to put DC-protection module very near UCD.
I am afraid that this can cause hum. I have strongly that kind of experience with my Linkwitz Orions XO. When transformer was in at same case that XO, it cause strong hum. After i put transformer in external case, hum disappeared totally.
I agree.
One more thing about Velleman K4700. It includes transformer and in my case i have to put DC-protection module very near UCD.
I am afraid that this can cause hum. I have strongly that kind of experience with my Linkwitz Orions XO. When transformer was in at same case that XO, it cause strong hum. After i put transformer in external case, hum disappeared totally.
Hi,
How about a crowbar + mains fuse type solution?
You can make a solide state relay with power mosfets as crowbar. Trip them on any number of conditions you like, DC offset, overtemp, undervoltage, whatever, should be able to dump the current repeatedly, can't reset until inspection because it blows the mains fuse, and has the advantage of shutting down the supply. It seems like it would be most transparent to the system as well.
Any transformers should be kept well away from your modules. I dont' see why a transformer can't be placed further away and use shielded wires to bring the outputs over to the relay/PCB.
Regards,
Chris
How about a crowbar + mains fuse type solution?
You can make a solide state relay with power mosfets as crowbar. Trip them on any number of conditions you like, DC offset, overtemp, undervoltage, whatever, should be able to dump the current repeatedly, can't reset until inspection because it blows the mains fuse, and has the advantage of shutting down the supply. It seems like it would be most transparent to the system as well.
Any transformers should be kept well away from your modules. I dont' see why a transformer can't be placed further away and use shielded wires to bring the outputs over to the relay/PCB.
Regards,
Chris
classd4sure said:
Not any other reason but quite limited space in my current slim line 4-ch case. Anyway, i think it is possible to arrange needed space with little re-arragement of layout.
Cheap soft-start:
Gentlemen, I had this silly idea about a cheap "soft-start" (I prefer to invest in PS caps).
My amp's power supply powering-on is like a religious ceremony that I do seldom, because they are practically allways on. I prefer to use the modules' power-on capacity also, with a toggle switch.
Then I thought:
"why don't I use a double path start circuit with 220R/10W paralel to a secondary wire, each with its own power button. I put power on the R path then I count 8 seconds and switch on the secondary path- just imitating a soft-start circuit?"
Then I could even put-off the R path.
This could save me a few $ 😉
What do you think?
Mauricio
Gentlemen, I had this silly idea about a cheap "soft-start" (I prefer to invest in PS caps).
My amp's power supply powering-on is like a religious ceremony that I do seldom, because they are practically allways on. I prefer to use the modules' power-on capacity also, with a toggle switch.
Then I thought:
"why don't I use a double path start circuit with 220R/10W paralel to a secondary wire, each with its own power button. I put power on the R path then I count 8 seconds and switch on the secondary path- just imitating a soft-start circuit?"
Then I could even put-off the R path.
This could save me a few $ 😉
What do you think?
Mauricio
Re: Cheap soft-start:
That's similar to my current plans, but why bother to simulate a soft start? For very little extra effort or money you can make it alot better.
Double path start circuit is just = DPST relay.
You only need one set of normally closed contacts to short out the series power resistors that limits the current to soft start.
Get a very small auxiliary transformer and make a very cheap low voltage DC supply to fire the soft start relay. Connect them to mains through a DPST switch with an appropriate fuse in front of it.
Immediatly after the switch you place your second take off and fused mains feed right to your small auxiliary transformer, from which you add a bridge rectifier to charge a fairly small valued cap say 100uF, the simplest regulator you want and any common variety delayed on relay driver circuit, like a few transistors driven by an RC network.
Then you can use a 12V relay to automatically and very reliably short out your measly 10 watt power resistor safely.
You can simply use the secondary set of NO open contacts of the soft start relay, in series with a toggle switch, to create an AND function which I think would be pretty fail safe under all conditions.
If you lose power it has to go through soft start before the modules get enabled. Upon even fairly rapid power cycling it should work very well unless you overheat your resistor. I've found "thick film" power resistors which are in a TO-220 type package which you can attach a small heatsink to, with resistor element electrically isolated from the case, available at digikey for about 8$ and can handle 25W.
You can do it all up P2P on a cheap veroboard surplus bought or as found on ebay.
Got mine from Radio Shack.
You know even if you say there's no way anyone will ever use the amp but me ..... in this world today even if someone breaks into your house and steals your amp from you, takes it home turns it on, leaves and a fire starts that kills his family, he could probably sue you for everything you had. Build it safe.
Regards,
Chris
maxlorenz said:
That's similar to my current plans, but why bother to simulate a soft start? For very little extra effort or money you can make it alot better.
Double path start circuit is just = DPST relay.
You only need one set of normally closed contacts to short out the series power resistors that limits the current to soft start.
Get a very small auxiliary transformer and make a very cheap low voltage DC supply to fire the soft start relay. Connect them to mains through a DPST switch with an appropriate fuse in front of it.
Immediatly after the switch you place your second take off and fused mains feed right to your small auxiliary transformer, from which you add a bridge rectifier to charge a fairly small valued cap say 100uF, the simplest regulator you want and any common variety delayed on relay driver circuit, like a few transistors driven by an RC network.
Then you can use a 12V relay to automatically and very reliably short out your measly 10 watt power resistor safely.
You can simply use the secondary set of NO open contacts of the soft start relay, in series with a toggle switch, to create an AND function which I think would be pretty fail safe under all conditions.
If you lose power it has to go through soft start before the modules get enabled. Upon even fairly rapid power cycling it should work very well unless you overheat your resistor. I've found "thick film" power resistors which are in a TO-220 type package which you can attach a small heatsink to, with resistor element electrically isolated from the case, available at digikey for about 8$ and can handle 25W.
You can do it all up P2P on a cheap veroboard surplus bought or as found on ebay.
Got mine from Radio Shack.
You know even if you say there's no way anyone will ever use the amp but me ..... in this world today even if someone breaks into your house and steals your amp from you, takes it home turns it on, leaves and a fire starts that kills his family, he could probably sue you for everything you had. Build it safe.
Regards,
Chris
Maxlorenz,
I`ve been using such a soft start for many years.Mine use 470ohm 20watt resistors with a non latching push switch directly at the side of the main breaker switch. Such a combination does away with fuses and relay contacts and thus unnecessary dry and soldered joints.
Measurements reveal the voltage peaks after approx. 3 seconds of operation.
Bob Lewis
I`ve been using such a soft start for many years.Mine use 470ohm 20watt resistors with a non latching push switch directly at the side of the main breaker switch. Such a combination does away with fuses and relay contacts and thus unnecessary dry and soldered joints.
Measurements reveal the voltage peaks after approx. 3 seconds of operation.
Bob Lewis
BOB LEWIS said:
To do away with the fuses takes a very carefully selected breaker, what type are you using?
I'd opt for a magnetic hydraulic dpst perhaps with a few extras but that's very expensive and it's hard to find any that are rated for use as primary means of protection _and_ as primary power switch that enforce no reset while tripped.
I have found some that actually look nice, are rated as primary switch, but require a supplementary means of protection like a fuse.
Regards,
Chris
Pasi P said:
I use the main tranformer for the supply of my protection circuit. Just rectify it and bring it down to a safe voltage for the protection pcb.
Otherwise put it a bit away from the UCD's. Or replace the small transformer with a small toroid, they have less radition. I have my UCD's quit near the big main toroid in my housing and have no humm at all.
Bert,
Thanks again. Very valueable information from you.
I think i will give it change to show its "performance". Velleman K4700 kit is available also in Finland so it is easy to try it.
I wonder how difficult it has been to find some suitable dc-protection to UCD.
Thanks again. Very valueable information from you.
I think i will give it change to show its "performance". Velleman K4700 kit is available also in Finland so it is easy to try it.
I wonder how difficult it has been to find some suitable dc-protection to UCD.
Pasi P said:
Yes, please do. Better have protection for your speakers. I cannot understand people having amps. without proper protection. Your speakers are far more expensive(mostly) than your amps. Cannot find the picture of your housing so I could see where it should fit best.
Pasi P said:
I'm pretty sure you can use any DC protection you like with it, some are just more effective than others, with the limitations being either what kits you can find or what you can build yourself.
Aside from protecting equipment Bruno has pointed out it's a fire hazard not to have it because DC heats the voice coil.
My speakers aren't terribly expensive and will cost less than the amp, yet I'm very happy with them! They have 3 amp slow blow fuses in them so luckily enough I don't have to worry about it.
If I had better speakers I wouldn't go throwing a fuse in either, but if they're mediocre like mine, go for it.
Is there somewhere published FFT plots of UCD(180) amps?
If not, would it be possible for someone to make FFT plot for example at 1khz and 1/10 (+1/2) power? I am curious about spectral distribution of distortion components in these...
If not, would it be possible for someone to make FFT plot for example at 1khz and 1/10 (+1/2) power? I am curious about spectral distribution of distortion components in these...
I'm not familiar with the term crowbar, but I remember a post some time ago (maybe another forum?) where mosfets we're used for dc protection.classd4sure said:
The way you describe it, it sounds ideal. Why are we not seeing more of this type of protection circuit?
Could you define 'well away' in units of measurement? What would be a reasonably safe distance?
Regards,
Hans.