DISCOVERED NEW PRODUCTS
New product announcements are made
nearly every day. I subscribe to many trade journals and each is filled with hundreds of
flashy advertisements. But, only a few of those product ads catch my eye. Since I’m
a circuit designer, I especially like those components that trigger many new application ideas
in my mind. Sometimes it is the smallest products that are the most useful.
Tiny surface mounted components that perform a nice little
function have countless applications. I also like anything that keeps battery power
consumption low. These days you can do many interesting things with a well-designed
circuit powered from just a few tiny button battery cells.
I often discovered new products in surplus electronic catalogs.
The surplus companies often buy up stock that came from companies that went out of business.
Bad marketing or bad management may have killed a perfectly good product idea. Their loss
can be your gain if you can spot the bargain.
David A. Johnson, P.E.
Discovered New Products:
|80A Latching Relays from KG
I love the idea of a relay
which can handle lots of power with very little extra energy. Most relays draw
constant power to keep contacts closed. Latching relays have two stable
mechanical states. These devices can be opened or closed with a short 20ms 12v
pulse. The lack of a constant coil current can really add up in power savings.
Applications for these things are endless. There are a lot of off-grid solar
power systems which use large battery banks. Battery power sometimes has to be
disconnected when the battery voltage drops below a critical point. This is a perfect
application for a latching relay. Likewise, when a battery is fully charged, power to
the battery may have to be disconnected to prevent battery overcharging. Also,
as can often happen with wind generators, power from the wind turbine may have
diverted away from the battery to either a dummy resistive load or some other energy
storage system, when the battery is full and there is excess wind energy. All of
these applications could be handled with these beefy latching relays. A 200 Amp
relay used in a 48v DC battery bank could handle nearly 10KW of power.
KG Technologies Latching Relays, 80A
80 Amp Relay
200 Amp Relay
|Crank Style LED Flashlight from
The crank generator type
flashlight shown below produces a nice bright light from three focused white LEDs.
I opened the assembly up and disconnected the brush type generator. With
vigorous cranking I measured the output at 5v DC into a 12 ohm load, which means 400ma
of current. The rechargeable lithium battery measured 20mm in diameter and 3mm
thick. Based in this information, I would guess that the Amp-hour capacity of the
battery would be about 50ma-hours. If the current through each LED was set at
about 20ma, that put the operational time at around 1 hour with a fully charged
The circuit used a bridge rectifier, so the crank
motion could go clockwise or counterclockwise. There does not appear to be any
voltage control, so the battery could be damaged due to overcharging.
It would be interesting to try use the 2 watt
generator for some other applications. At the very least, with this kind of
flashlight product, the lithium ion battery size could be increased to perhaps a full
Amp-hour. That would allow the unit to operate for a much longer time. A
fully discharged battery might take a full hour of vigorous cranking to charge the
thing up. Once charged, the larger battery should keep the light going for perhaps 12
or more hours. The +5v output should be able to feed power into a cell phone as
|High Capacity Lithium Coin Cell --
1 Amp-hour Lithium Battery from Panasonic
A while back I had a project which needed a 3v battery.
The product needed to operate for more than a year between battery changes. The
current draw was such that the battery had to have an Amp-hour rating in excess of
750ma-hours. A couple AAA or AAA cells would have worked but they took up quite
a bit of space. After looking around, I found a nice lithium coin cell and
holder which were perfect for my application. The Panasonic CR2477 has a
1000ma-hour rating. The cell diameter is only 24mm. A battery holder from
Memory Protection Devices makes for an easy battery replacement.
Battery = Panasonic CR2477
Battery Holder = Memory Protection Devices BH1000-G
|HP 35s RPN Calculator --
HP35s RPN Scientific Calculator from HP
Some 30+ years ago, I worked for Hewlett Packard (HP)
down in Colorado Springs Colorado. Back then, any calculations had to be done
with mechanical slide rules. In 1972, HP came out with their first line of
scientific calculators, the HP35 as shown below. I was able to get a big
discount and so I bought my first RPN (reverse Polish Notation) machine. If you
have never used a RPN calculator, you should try one. The method requires fewer
key strokes and is perfect for many complex scientific calculations. After 30
years of using RPN calculators I would never want to use anything else. My original
HP35 still sits on my work bench, where I often use it to calculate needed component
values. Few electronic products can boast valuable services for 30+ years.
To celebrate the 35 years since the original HP35, HP
decided to release the HP35s. As shown below, it has a lot more features than
the 35 and still uses the wonderful RPN notation.
|Liquid Cooled LED Light --
Liquid Cooled LEDs from Eternal LED
Light emitting diodes (LEDs) are becoming more and more
popular. However, in spite of their high efficiency, they still do produce some
heat. Heat has been attributed to the slow degradation and fading of many power
white LEDs. So, there have been many attempts to get rid of that extra heat from
the part. Some systems have been using aluminum fins and even some cleaver
electric fan designs. A company called “Eternal LED” has a neat idea of using
paraffin wax surrounding the white LED inside their Edison base lamp assembly to keep
the device cool. It appears that the case is plastic. Once heated, the wax
forms a viscous fluid, which can efficiently move heat away from the parts inside the
assembly to the walls of the lamp, where it can be dissipated. The solid to
liquid phase change of the wax also helps to remove excess heat through “heat of
fusion” physics. I might try using this technique myself in some LED lights I
have in mind. The liquid cooling concept could work in other geometries, such a
square or even flat light fixture shapes.
The HydraLux-4 LED bulb uses just 4 watts of power
yet produces as much light as 25w incandescent lamp. The lamp is a bit pricey at
$35 each but for some applications, where lamp access is difficult, it might be worth
Enternal LED website =
|LT3092 Programmable Current Source
LT3092 Programmable Current Source from Linear Tech
||This is a neat part. I can
imagine all kinds of applications for it. It is basically a three pin part.
The input can range from 1.2v to 40 volts. The output current can range from
300uA to as high as 200ma. However, the power dissipation shouldn’t exceed
about one watt. So, at the full 200ma, the voltage drop shouldn’t be allowed to
exceed 4 volts.
The nifty feature of this
part is that the output current is set with two external resistors. The ratio of
the two defines the output current. Typically, the set resistor is 20K. With a
20 ohm output resistor the current would be programmed for 20ma.
|One application for this part is
shown below. The LT3092 is programmed for a 100ma current source. Its output is
connected to an unknown large value capacitor.
By setting up an oscillator with a 1 volt trip
voltage, a positive ramping voltage is produced across the capacitor. The ramp
timing is determined by the equation dV/dT = I/C. If dV is 1 volt and I is 0.1
Amp then dT will be 10 seconds for a 1 Farad capacitor. The capacitor value is
|Magic Jack Voice Over IP --
Magic Jack Voice Over IP Service
A couple months ago my 84 year old mother in-law stayed
at my house while she recovered from a stroke. To help her cope with being away
from her Texas home and all of her friends there, we bought her a Magic Jack for $40.
The device plugged into my laptop computer and into an extra cordless telephone system
I had on hand. With this system my mother in-law was able to pick up the phone
and make calls to Texas without any additional long distance charges.
No, it was not a perfect system. There were some
dropped calls, missed calls and at times there was excessive noise. Installation
of the Magic Jack was a snap and overall I was very pleased with the service.
We did get the impression from the TV and Internet ads that by getting a Texas area
code, people in that area code could call my mother in-law in Colorado without them
being charged for a long distance charge. However, the calls were treated as a
long distance call for them. In spite of some negatives, I still would highly
recommend this device. I know my mother in-law appreciated having the freedom to
make lots of calls and talk as long as she wanted.
Long before rechargeable batteries become available, the
1.5v zinc carbon battery was the gold standard for flashlights and portable electronic
devices. They were used everywhere. To this day, many portable electronic devices
and flashlights rely on 1.5v disposable alkaline batteries as their primary energy
source. Many flashlights and electronic devices will only work with alkaline
batteries. Still other electronic devices monitor the battery and will shutdown when
the voltage drops below a certain minimum level. Often when 1.2v rechargeable NiMH
batteries are used, the electronic device will stop operating long before all the
energy stored in the rechargeable battery has been depleted. Enter the 1.6v
nickel-zinc battery. The slightly higher voltage usually means operating times that
are comparable to 1.5v alkaline batteries with the added advantage of being a
PowerGenix seems to be the dominant player in these
new batteries. Their AA cell offers a 1.65v voltage and a 1.5 Amp-hour capacity. This
gives a total of 2.5 watt-hours of energy storage. This is lower than a 1.2v 2.5
Amp-hour NiMH rechargeable cell, which has 3 watt-hours of stored energy. But, the
higher voltage may indeed mean longer operating times for a lot of portable electronic
gear. As an added benefit, the battery is about 30% lighter in weight. Look for
PowerGenix blister packs and matching chargers.
Cells AA Cell Charger
|Rohm BU52014HFV Hall Magnetic Field
Sensor -- BU52014HFV Hall Sensor
I have big plans for
this part. It performs many of the tasks I was going to do using a bunch more
parts. Inside this tiny part is a sensitive Hall Effect magnetic field sensor,
some logic, timing circuits and two latched CMOS outputs. One output changes
state when the sensor detects a north pole magnetic field and the second output is
activated with a south pole field. The real beauty of this part is that is does
this while drawing only 12 microamps of current at 3 volts. I’m going to design
a nice battery charge current indicator using thing part. The battery powered
indicator will show which direction current flows. A green LED will show current
going into the battery and a red LED will show current flowing out of the battery.
If I flash the LEDs I can operate the indicator for years from one 3vbattery.