I am building a AMB o11 power supply and I could use some help with the transformer wiring. I am attaching a couple of photos showing the primary/secondary and transformer schematic along with the power supply connections. My questions are how should I wire the primaries for 115 volt and how should I connect the secondaries to the power supply?
Thanks for any replies.
Thanks for any replies.
Attachments
For 120VAC operation only :
Primary: connect red to red.....connect black to black ..... (120VAC primaries connected in parallel, in phase)
Secondary: From The σ11 regulated power supply
the secondaries are connected in series, with phasing to add the voltages (+ connected to -).
Number the terminals from left to right, 1 2 3 4 (pins #2 and #3 are internally connected together).
The two secondaries are interchangeable. Ohm out the secondaries to make that sure you use the right wires.
terminal 1: blue (secondary #1)
terminal 2: green (secondary #1)
terminal 3: blue (secondary #2)
terminal 4: green (secondary #2)
Did you get the right transformer voltage for the circuit? Input will be twice the rated 15VAC secondary voltage.
In other words, the input to the board will be 30VAC, is this what you need?
Primary: connect red to red.....connect black to black ..... (120VAC primaries connected in parallel, in phase)
Secondary: From The σ11 regulated power supply
the secondaries are connected in series, with phasing to add the voltages (+ connected to -).
Number the terminals from left to right, 1 2 3 4 (pins #2 and #3 are internally connected together).
The two secondaries are interchangeable. Ohm out the secondaries to make that sure you use the right wires.
terminal 1: blue (secondary #1)
terminal 2: green (secondary #1)
terminal 3: blue (secondary #2)
terminal 4: green (secondary #2)
Did you get the right transformer voltage for the circuit? Input will be twice the rated 15VAC secondary voltage.
In other words, the input to the board will be 30VAC, is this what you need?
Last edited:
rayma, thank you for replying and for the information.
The transformer spec. for the 12 volt output I need is quoted by AMB as:
"For 12VDC Output = 15V (or dual 8V in series)"
And:
"Power transformer - Single-secondary, dual-secondary and center-tapped secondary transformers are supported. Toroidal type is recommended for minimum stray magnetic field. The following table lists the transformer secondary recommendations for various output DC voltages.
For other output voltages, a rule of thumb for this PSU is that approximately 7V drop should be maintained across the pass MOSFETs under load. This allows for the 2V Vgs of the MOSFETs plus about 5V of headroom to allow for line voltage fluctuations. Using the 24V output as an example, the pre-regulator voltage should be 31V. Accounting for a couple of volts drop across the rectifier diodes, that figure goes up to 33V. The transformer voltage should be 0.707 times that of the rectified DC voltage, so 33V * 0.707 ~= 23V. Thus, a 24V or dual 12V transformer should work well."
The transformer spec. for the 12 volt output I need is quoted by AMB as:
"For 12VDC Output = 15V (or dual 8V in series)"
And:
"Power transformer - Single-secondary, dual-secondary and center-tapped secondary transformers are supported. Toroidal type is recommended for minimum stray magnetic field. The following table lists the transformer secondary recommendations for various output DC voltages.
For other output voltages, a rule of thumb for this PSU is that approximately 7V drop should be maintained across the pass MOSFETs under load. This allows for the 2V Vgs of the MOSFETs plus about 5V of headroom to allow for line voltage fluctuations. Using the 24V output as an example, the pre-regulator voltage should be 31V. Accounting for a couple of volts drop across the rectifier diodes, that figure goes up to 33V. The transformer voltage should be 0.707 times that of the rectified DC voltage, so 33V * 0.707 ~= 23V. Thus, a 24V or dual 12V transformer should work well."