Hi Folks,
I live off-grid on a sailboat. My only power comes from a solar panel/controller/storage battery. To get audio I have been using small classD amps. So far so good. I have been missing my tube amps and related distortion and so have been exploring possibilities of a small tube amp running from my 12v system. I found an Elekit PCL86 amp that runs from a 12v/4a SMPS...got me thinking (always trouble 😉. How can I limit the current going into the power supply board of the amp circuit to 4 amps max? I do not have or plan to have an inverter. The Elekit TU8100 uses ICs and a transformer to provide the B+, etc for the tubes. I would like to take the SMPS (12v/4.17a) out and directly power with my battery. How? Thanks...
I live off-grid on a sailboat. My only power comes from a solar panel/controller/storage battery. To get audio I have been using small classD amps. So far so good. I have been missing my tube amps and related distortion and so have been exploring possibilities of a small tube amp running from my 12v system. I found an Elekit PCL86 amp that runs from a 12v/4a SMPS...got me thinking (always trouble 😉. How can I limit the current going into the power supply board of the amp circuit to 4 amps max? I do not have or plan to have an inverter. The Elekit TU8100 uses ICs and a transformer to provide the B+, etc for the tubes. I would like to take the SMPS (12v/4.17a) out and directly power with my battery. How? Thanks...
Hi, the amplifier specification is 2A @12V, rgds, sreten.
Being class A, current draw will be constant.
A tube buffer with class D might be a better
idea for power output and battery drain.
Being class A, current draw will be constant.
A tube buffer with class D might be a better
idea for power output and battery drain.
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I understand the tube buffer/classD idea. I like output transformers, and low wattage is no problem...So, how can I limit inflow of current from battery to amp?
V= I x R so
I = V / R
I is current - V is volts - R is resistance.
So current is controlled by the voltage supplied to the amplifier divided by the resistive load of the amplifier.
The amplifier draws 2A at 12V DC so must have a resistive load of 6 ohms, and draw 24watts.
The switch mode PSU was rated at 4A 12V so has 2a in reserve.
The only way to vary the current that the amplifier draws is to vary the voltage.
As long as the amplifier does not mind being run from the varying voltage from the solar system it should just work.
Remember a fully charged battery is probably 13.8V and in an alternator system a battery voltage can be as high as 14.4V when the alternator is charging.
I = V / R
I is current - V is volts - R is resistance.
So current is controlled by the voltage supplied to the amplifier divided by the resistive load of the amplifier.
The amplifier draws 2A at 12V DC so must have a resistive load of 6 ohms, and draw 24watts.
The switch mode PSU was rated at 4A 12V so has 2a in reserve.
The only way to vary the current that the amplifier draws is to vary the voltage.
As long as the amplifier does not mind being run from the varying voltage from the solar system it should just work.
Remember a fully charged battery is probably 13.8V and in an alternator system a battery voltage can be as high as 14.4V when the alternator is charging.
Hi,
The inbuilt SMPS (presumably) cannot be current limited.
The amplifier will draw a given current for a given voltage.
Presumably the SMPS can handle various input voltages.
rgds, sreten.
The inbuilt SMPS (presumably) cannot be current limited.
The amplifier will draw a given current for a given voltage.
Presumably the SMPS can handle various input voltages.
rgds, sreten.
Thanks for the replies.
SMPS is not built into unit, it is external...
DC plug is usual 5.5mmx2.1mm
Question is how to limit current going into input plug from battery so as not to blow the ICs, resistors, caps, and step-up transformer of the power supply circuit of amp that is designed for a 12v/4a SMPS?
SMPS is not built into unit, it is external...
DC plug is usual 5.5mmx2.1mm
Question is how to limit current going into input plug from battery so as not to blow the ICs, resistors, caps, and step-up transformer of the power supply circuit of amp that is designed for a 12v/4a SMPS?
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@Xoc1,
solar controller charges at 14.1v and I realize battery is not at 12v. I do intend on running amp at night when sun has set...heck it is in the 90's F here...don't need a heater.
What I think I need is a regulating DC-DC circuit that outputs 12v/4a...
Or?
solar controller charges at 14.1v and I realize battery is not at 12v. I do intend on running amp at night when sun has set...heck it is in the 90's F here...don't need a heater.
What I think I need is a regulating DC-DC circuit that outputs 12v/4a...
Or?
Hi,
I presume the valve HT is generated by a SMPS.
Same for the heater supplies DC converter.
It should be fairly liberal about input voltage.
rgds, sreten.
All 12V stuff can handle 13.8V and probably 15V.
I presume the valve HT is generated by a SMPS.
Same for the heater supplies DC converter.
It should be fairly liberal about input voltage.
rgds, sreten.
All 12V stuff can handle 13.8V and probably 15V.
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I know what you think you need. I tried to explain why you don't need it.
When you fit a bulb or any other 12v equipment to your boat do you need to use a current limiter? No. Why? Because its designed to draw the right current at 12 volts.
Want to blow it up? you will need to increase the voltage considerably then it will draw more amps and burn out.
When you fit a bulb or any other 12v equipment to your boat do you need to use a current limiter? No. Why? Because its designed to draw the right current at 12 volts.
Want to blow it up? you will need to increase the voltage considerably then it will draw more amps and burn out.
Why else do you need to limit the current that the supply can provide to the amplifier, if not for fault conditions?
Hi,
The OP seems to think current can be limited and it still works.
Its not about protecting fault conditions.
rgds, sreten.
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Indeed what the original poster is trying to do does not make sense. What are you trying to do in the big picture?
There are commercial battery protection devices, for example current limiters for the 2nd battery in a dual battery system, or battery isolators that isolate the battery if voltage drops below a certain threshold. Are you conflating what these devices do and what your needs are?
There are commercial battery protection devices, for example current limiters for the 2nd battery in a dual battery system, or battery isolators that isolate the battery if voltage drops below a certain threshold. Are you conflating what these devices do and what your needs are?
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I've re-read this thread several times now, and all I can say is that my interpretation of OP's questions differs significantly from yours.
Quoting OP:"Question is how to limit current going into input plug from battery so as not to blow the ICs, resistors, caps, and step-up transformer of the power supply circuit of amp that is designed for a 12v/4a SMPS?"
Those sound like fault conditions.
OP wants to replace a nominally 12V 4A supply (presumably from AC mains power, but he's on a boat so would need an inverter) with a nominally 12V car battery that he appears to correctly surmise can supply more than 4A. OP appears to share the misunderstanding of an awful lot of EE Senior Design students that being ABLE to supply more current means that it WILL supply more current, whether the amp needs it or not, and consequently blow up the amp. Many people find this non-intuitive, it's no shame.
Since the correct answer is that the car battery won't supply any more current than the amp demands, there is no need to limit the current for normal operation. If, on the other hand, someone (e.g.) accidentally spills a beverage or salt water into the amplifier it could very well fail in way that causes excessive current to flow which could in turn induce additional failures like blown speaker coils, burned power wires, etc. In that case, some mechanism to prevent this excessive current is very useful - like a fuse.
I suspect the OP thinks that attaching a 12V,200A supply to a device which requires 12V,4A max may overload it - where will the other 196A go? This is a common misconception.
In such situations it is not the 12V,4A device which needs any protection but the wiring. A fuse or circuit-breaker will do this; most 12V distribution systems include these as standard.
In such situations it is not the 12V,4A device which needs any protection but the wiring. A fuse or circuit-breaker will do this; most 12V distribution systems include these as standard.
Hi All,
Back on land. I believe you are all correct that the OP's (me) understanding of the situation is faulty...mea culpa. A fuse would protect from fault condition (as Infinia and others posted) and amp will only draw what it can (which appears to be 2A fixed for Class A operation. Thanks for this very elementary lesson in electronics. I listen to music with amps and speakers but obviously have no real knowledge of basic electronic theory and physics. So, thanks to you all...even an old dog may learn new tricks😉
Back on land. I believe you are all correct that the OP's (me) understanding of the situation is faulty...mea culpa. A fuse would protect from fault condition (as Infinia and others posted) and amp will only draw what it can (which appears to be 2A fixed for Class A operation. Thanks for this very elementary lesson in electronics. I listen to music with amps and speakers but obviously have no real knowledge of basic electronic theory and physics. So, thanks to you all...even an old dog may learn new tricks😉
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