New logic circuit PSU transformer

I call back that last update (see previous post). Apparently the transformer wasn’t sufficient after all due to lack of mechanical protection of windings. The safety standard for transformers, EN 61558-1, requires that insulation must not be easily damageable during device assembly. So windings must be mechanically protected from being hit by other objects.

Luckily I found near perfect “drop-in” replacement for the transformer. This model actually probably would have been chosen in the first place if it were available at the time of logic circuit PSU design. The new transformer type was just introduced to market at late 2012.

The new transformer mounted with "3D" installation method

The new transformer mounted using the “3D” installation method familiar to all tinkerers

Safety checking results

Today I got first results from the accredited testing service for compliance of power drive safety standard EN 61800-5-1. They did good job and found few issues:

  1. Isolating transformer between user touchable and hazardous voltage side doesn’t meet reinforced isolation requirements
  2. Clearance from power stage & bridge rectifier mounting screws to PCB tracks not large enough
  3. On one side of the enclosure the vent holes are too large to meet IP30
Isolating transformer (blue) has 3 kV isolation spec

Logic power isolating transformer (blue) has 3 kV isolation spec but still doesn’t meet the strictest interpretation of  the safety standard

Luckily none of them is hard to fix but finding them early was very important!


By contacting transformer manufacturer we learned that the blue winding consists triple insulated teflon wire which fulfills the reinforced isolation standards. If we can confirm that, we save few days of isolated PSU circuit redesign & testing!

Laser diode drivers & Quick update

This week I have been wandering around Photonics West exhibition at San Francisco. I have been collecting leads for our new product area: laser diode drivers. LD drivers are a natural expansion to motor drives category as they share many of the closed loop current control technologies. Check out Intensify Nx50 product site!

Intensift Nx50 laser diode driver

Intensify Nx50 laser diode driver

Meanwhile Argon prototype has been sent to a reputable standard verification company to ensure it’s compliance to EN 61800-5-1 safety stadard. Safety is a highly critical part to get correct as failures to comply could become very expensive. Granite Devices is taking product liability seriously.