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The Varilight one is fine. It doesn't have an AC output at tens of kHz...
LED flicker
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The Varilight one is fine. It doesn't have an AC output at tens of kHz...
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So what frequency is the output? There is nothing to say in the link and it looks far to small to have a 50Hz output at 50 watts.
This: https://www.tlc-direct.co.uk/Products/TLT50slash1.html? I linked to earlier is cheaper and definitely 50Hz output so why risk something not known.
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The output is 50Hz. Having taken one apart, the switcher frequency is 250kHz and has LC filtering on the output so no 250kHz component is present up to it's maximum load.
Interesting. I will get one and investigate myself.
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Winston it is £6 more expensive. The Varilite is £11 to TLCs £17. aptsys, it seems to fit the bill at 50w max and no minimum watts, readily available and cheap enough. I have found Varilite stuff decent quality in the past.
Some LED drivers may require that the supply to them is AC at 50 Hz to ensure the driver operates correctly. They may use a capacitor to limit current drawn from the supply and this would require AC to be able to pass any current and the amount of current would increase as the frequency increased.
Other LED drivers may work well with either an AC or DC supply of the correct voltage and, if AC, a frequency higher than 50 Hz but not much higher ( 100 Hz maybe ).
I made a mistake. sorry.
I would have thought that the fact the manufacturers state DC or 50/60 Hz AC would answer that question.
Well I've got hold of one of the Varilite SMPSs. On connecting it up and looking at the no load output with a scope it looks like 50Hz. But winding the timebase up shows that there is plenty of approx 300kHz modulated at 50Hz. In fact just like any other SMPT except this one shows it at no load.
I put a small load on it a 2.2W lamp and it worked OK. Likewise with a 35 watt lamp. Turned it off and went to find a GU10 size LED. Connected it up, nothing. Further investigation with the scope showed the SMPT had died, there only being a few very small spikes on the output.
So, not impressed with reliability. It will go back tomorrow. Watch this space.
I put a small load on it a 2.2W lamp and it worked OK. Likewise with a 35 watt lamp. Turned it off and went to find a GU10 size LED. Connected it up, nothing. Further investigation with the scope showed the SMPT had died, there only being a few very small spikes on the output.
So, not impressed with reliability. It will go back tomorrow. Watch this space.
Was it pure 50 Hz sine as in the upper trace or pseudo sine ( half cycles filled with the 300kHz ) as in the lower trace. ( Traces are replicated images )
Lower trace.
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Mine looked like the top trace, and obviously the bottom one before the filter. Not sure what winston did to break his though - they've been very reliable in the units I've observed.
So the next question which is the base line on the oscilloscope when viewing the wave form. Zero volts is the equivalent of the Neutral
For a 12 volt output use +12 -12 and 0 +24
Often the DC offset pseudo AC does not reach 0 volts always being at least a volt or two above zero. That this pseudo AC never has a zero value can "confuse" switch mode devices that are expecting to be supplied with AC that has 100 zero crossing points per second at 50 Hz and not pseudo AC which may not have any zero crossing points.
For a 12 volt output use +12 -12 and 0 +24
Often the DC offset pseudo AC does not reach 0 volts always being at least a volt or two above zero. That this pseudo AC never has a zero value can "confuse" switch mode devices that are expecting to be supplied with AC that has 100 zero crossing points per second at 50 Hz and not pseudo AC which may not have any zero crossing points.
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