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Please select from
the list below or the links on the right.
Vintage Knife
Switches
The "knife switch" is the simplest
form of switch that easily demonstrates the functioning of a switch. Old sci-fi
movies ("Frankenstein (1931)" or "Young Frankenstein (1974)" , for example),
made extensive use of these switches in the laboratory scenes.
Today, use of simple knife switches is limited to educational projects,
classroom and demonstration purposes - science projects for example.
Basics of Knife Switches
A simple knife switch has a metal lever that comes into contact with
a metal slot to create a contact.
The lever is insulated at the 'free end' with a plastic handle.
Since the electrical connections are exposed, knife switches are never
seen in household wiring.
Simple Switch or SPST
Knife Switch
The simplest knife switch is a Single Pole
Single Throw (or SPST) switch. This means that it controls one wire
(pole) and it makes 1 connection (a throw). Yes, this is an on/off
switch, but a 'throw' only counts when a connection is made. 'Off' is
not considered a 'throw'. Also notice that only 1 wire has to be
switched.
SPST switches are used to control one
device at a time such as one light bulb or one electric fan. |
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| SPST Knife switch has two contact
screws for connecting the wires. Diagram in the right shows a simple
knife switch. One wire connects to the contact screw on the lever side.
The other wire connects to the contact screw in in slot side. To make a
secure contact first loosen the screws, then place the wire under the
screw cap, make a tight loop and finally tighten the screw. |
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If you are using insulated wire, you must
remove the insulation (plastic shield) from 1/2 inch of the wire end
before making the contact. For the best possible contact, use wire gage
32 up to 20.
Product Code: KSWITCH
DPST Knife Switch
(Double Pole Single Throw)
DPST switches control two wires
(poles) and makes 2 connections (throws). This is like two separate
simple on/off switches that act together.
DPST switches are used to control two
devices at a time such as one light bulb and one electric fan. |
See price and availability |
DPST Knife switches have four contact
screws for connecting the wires. To make a
secure contact first loosen the screws, then place the wire under the
screw cap, make a tight loop and finally tighten the screw. If you are using insulated wire, you must
remove the insulation (plastic shield) from 1/2 inch of the wire end
before making the contact. For the best possible contact, use wire gage
32 up to 20.
This switch has two mounting holes.
DPDT Knife Switch
(Double Pole Double Throw)
| A Double Pole Double Throw (DPDT)
switch is a switch that has 2 inputs and 4 outputs; each input has 2
corresponding outputs that it can connect to.
Each of the terminals of a double pole
double switch can either be in 1 of 2 positions. This makes the the
double pole double throw switch a very versatile switch. With 2 inputs,
it can connect to 4 different outputs. It can reroute a circuit into 2
different modes of operation. |
View price and availability of KSWITCH22 |
A Double Pole Double Throw Switch is actually
two single pole double throw (SPDT) switches.
DPDT Knife switches have six contact
screws for connecting the wires. To make a
secure contact first loosen the screws, then place the wire under the
screw cap, make a tight loop and finally tighten the screw. If you are using insulated wire, you must
remove the insulation (plastic shield) from 1/2 inch of the wire end
before making the contact. For the best possible contact, use wire gage
32 up to 20.
This switch has two mounting holes.
Learn how to
design switch circuits!
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Distributors of scientific and educational products
Where to buy?
Most pictures are linked to
the pricing and online store for fast and convenient ordering
Our products are available at the following
online stores. For large orders please call in advance and verify the
availability, wholesale discounts and shipping options. If you cannot find any
product in the online store of your choice, please use the search option of the
store or call (973)777-3113 for further assistance.
All orders will be shipped from our
warehouse in United States (USA). We ship worldwide
to most countries including U.S., Canada, Australia, United Kingdom, New
Zealand, Germany, France, Netherlands, and many other countries.
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