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Dynaco ST150 PS Transformer

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I have a NOS power transformer which was used in the Dynaco 150 amp (part number 464 090). It is unused, leads not shortened, etc. It will provide either 50vdc or 70vdc +/- at 6 amps.

Besides being used in the ST-150 it was also used in the Dynaco ST-300.

A picture can be provided if anyone is interested. It is a little larger and heavier than the transformer in the Hafler DH200/220 amp. Below is the link for a schematic of the ST-150 PS in which this transformer was used.


Note that it has dual primaries suitable for either 120 or 240 VAC. So, it can be wired to provide several different secondary voltages. The higher voltage secondaries are booster windings of the same wire gauge as the other secondary. Therefore one can run full power on either set of secondaries.

What am I offered for this transformer? Any bids of $40 or more? Let me know of your interest. Thanks......

Here is a picture of this transformer compared to a Hafler DH-200 transformer. The ST150 transformer is on the right side. You can see it is a little larger. Also, it is a little heavier than the DH-200 transformer.


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The advantage of two sets of primary windings is the availability of twice the number of different voltages. The transformer I have can be used with either 120 VAC or 240 VAC, depending on how the two sets of primaries are wired.

To use this transformer with 120 VAC place the two sets of primary windings in parallel. To use it with 240 VAC place the two sets of primary windings in series with each other.

Now, if the input windings are placed in series and the transformer is used with 120 VAC you will get 1/2 of the voltages listed in the above messages. In other words, you will receive about 25 ± VDC after rectification with no load and with a nominal 120 VAC input.

Is 25 ± VDC close enough? In actual use the voltage will be slightly lower, depending on the load of your circuit.

You mention 110 VAC. Is this the level of AC voltage present at your home? If so the output as mentioned above would be about 22 ± VDC (110/120 * 25).

The output of a transformer is dependent on the input voltage which at my house will vary from 117 VAC to 124 VAC throughout the day and depending on the season (lots of air conditioners running), etc.

Let me know if this answers your question.
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