Steve, thanks for the feedback!
1. There are some typos in the DC/DC converter text
and schematic. The correct name is TPS62730.
2. The PUMH10 does use bipolar transistors, not
MOSFETs. As for driving the camera directly, note that the
pullup voltage on the camera is unknown. Some cameras
can be as high as six volts.
3. Correct. The CR2032 is a lithium manganese battery
with a floating voltage just above 3.0V. This is different than
common lithium-ion batteries which have a voltage of 3.6V.
4. There is an error in the figure. The 1M pulldown
resistor is supposed to be connected to "shutter," not
"detect." When unplugged, shutter and detect are shorted
together and the 1M pulldown serves to keep the circuit
off. When plugged, the detect line is isolated and will be
pulled up by the 10M resistor to turn on the device.
5. The choice of having a female connector on the
dongle was mostly driven by the cost of packaging. Putting
a single hole in the polycase enclosure is simply the least
As a final point, the battery life can be extended by
changing the inverter used in the circuit to a lower power
logic family (74AUP instead of 74AHC). The new part
number is Mouser #595-SN74AUP1G04DBVR. This is the
part we are shipping in the kits.
Michael Wieckowski, Ph.D.
I found a mistake in Figure 10 from my induction
charger project in the August 2013 issue. The current
limiting resistor "R8" should be connected to [IN] which is
the 4. 35 to 6. 5 volt input. To the left is a revised schematic.
Keeping Tabs on Batteries
Regarding Bryan Bergeron’s editorial from
the July 2013 issue on li-ion battery tech: Next
time, install the battery with a piece of paper
(a paper tab), blocking one pole from
connecting to the circuit. This is commonly
done with LED flashlights and kid’s toys.
I read Steve Borsher's letter regarding
tubes in the June 2013 issue with much
interest. I was a service tech at the Canadian
national distributer for Dynaco back in the late
‘70s and serviced many Dynaco amplifiers —
some of which were the MKIIIs and MKVIs.
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READER FEEDBACK Continued from page 26
48 September 2013