PDP-8 (Straight 8) Power Supply 40V Ripple

Current size small. Select new size for picture   Small ( 34K)  Medium ( 58K)  Large ( 79K)

Current size small. Select new size for picture   Small ( 34K)  Medium ( 58K)  Large ( 79K)

This shows the ripple on the 40V memory capacitors. One of the diodes was connected to the 40V tap and the other to the 45V tap. The 45V tap was supplying all the power to the supply. The red curve shows the large ripple at the AC line frequency due to the wiring error. With the wiring corrected the green ripple shows proper operation with the ripple at twice the AC frequency and reduced amplitude. The actual memory supply output goes through a linear regulator so the ripple is less.

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