Hello people,
I've built a linear type dual power supply for the purposes of driving low current op-amp audio circuits. The design is relatively simple; a 220v - 12v transformer which i'm actually running on UK mains (which reads (247-ish)... this subsequently boosts the output voltage to around 18v or so.
The waveform was little "bent-over" on the scope but once I smoothed it off with a few 4700uF electrolytics I had nice steady voltages. I've also used postive and negative vregs and a few 1uF ceramics for good measure. Finally i added an op-amp feeback loop setup on both sides with potentiometers so that i can control the voltages.
The circuit appears to working nicely although I haven't really applied any load yet apart from my scope and my multimeter.
The transformer I bought is a cheap chinese thing which i got off amazon for about 4 quid and it doesn't say the maximum current rating. All it says is 220V primary 12V secondary and 2 Watts of power. So I know that in order to calculate my current I can do P/V but should I use the primary V or the secondary. To make things more confusing I'm not actually getting the exact Voltage due to the tranformer being designed for EU mains.
If I measure the output of the Vregs (at maximum V) I get about 14V (+ and -) give or take a few millvolts which I’m guessing is just down to vreg’s tolerances. So If I do 2 Watts/ 14 Volts I get 0.142A. if this is correct then that’s not too bad seeing as though I only intent to use this power supply to drive a few op amps at a time and I can keep the gains low and leave the main workload to the power amplifier…. but am I calculating this correctly??
And also, do you think using this transformer may cause me problems? Seeing as firstly, it’s blatantly pretty poor quality (I can’t even find a datasheet for it) and secondly it’s not desgined for UK mains… that being said it does appear to be working okay.
Please see schematic attached.
Thanks in advance
I've built a linear type dual power supply for the purposes of driving low current op-amp audio circuits. The design is relatively simple; a 220v - 12v transformer which i'm actually running on UK mains (which reads (247-ish)... this subsequently boosts the output voltage to around 18v or so.
The waveform was little "bent-over" on the scope but once I smoothed it off with a few 4700uF electrolytics I had nice steady voltages. I've also used postive and negative vregs and a few 1uF ceramics for good measure. Finally i added an op-amp feeback loop setup on both sides with potentiometers so that i can control the voltages.
The circuit appears to working nicely although I haven't really applied any load yet apart from my scope and my multimeter.
The transformer I bought is a cheap chinese thing which i got off amazon for about 4 quid and it doesn't say the maximum current rating. All it says is 220V primary 12V secondary and 2 Watts of power. So I know that in order to calculate my current I can do P/V but should I use the primary V or the secondary. To make things more confusing I'm not actually getting the exact Voltage due to the tranformer being designed for EU mains.
If I measure the output of the Vregs (at maximum V) I get about 14V (+ and -) give or take a few millvolts which I’m guessing is just down to vreg’s tolerances. So If I do 2 Watts/ 14 Volts I get 0.142A. if this is correct then that’s not too bad seeing as though I only intent to use this power supply to drive a few op amps at a time and I can keep the gains low and leave the main workload to the power amplifier…. but am I calculating this correctly??
And also, do you think using this transformer may cause me problems? Seeing as firstly, it’s blatantly pretty poor quality (I can’t even find a datasheet for it) and secondly it’s not desgined for UK mains… that being said it does appear to be working okay.
Please see schematic attached.
Thanks in advance
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