Installation and service videos

Have you ever wondered how to learn to properly install or adjust a door closer, or what is involved in installing an automatic operator? Are you new to installing card access and want training on programming a new system?

A great source for this type of material is www.midwestwholesale.com. Under the “Education and Resource” tab, you will find a selection for Installation videos. Many major manufacturers have produced high quality videos covering installation and service of their equipment. In many cases, they will breakdown the installation of a specific model into three or four sections, and produce a three to ten minute video for each section. 

We currently have 115 videos from 14 different manufacturers. We are constantly adding content from all of the manufacturers we represent. These videos are all installation and/or service training material, not sales oriented.

Beware of the videos not produced by the manufacturer of the product. These are generally low quality and many contain inaccurate or misleading information.

Importance of a complete and accurate Bill Of Materials

One recurring issue I hear from many of our customers is problems resulting from an inaccurate bill of materials. The tech shows up at the job without everything he needs to complete the installation.

Material shortages or incorrect material can tank the project from a profit standpoint. It is not possible to overstate the importance of a complete and accurate bill of materials (BOM). Many times, in an effort to quickly get pricing for a project, sales/estimating may throw together a BOM, without committing a definitive scope of work to paper. While they may get most of the items needed on the BOM, it can be very easy to omit items such the required keyway, power transfer, or faceplate for an electric strike. 

You can build the BOM with a card reader, control panel, electrified mortise lock, power supply and access cards, but if you don’t include an electrified hinge, or you have a power supply with the incorrect voltage output, the project cannot be completed without additional trips, and wasted time. How often have you, or your employees had to make additional trips because you brought the wrong part(s)? Your errors and omissions are generally not considered a valid reason for a billable change order. If you were installing this equipment for a customer next door to your office and had the wrong hinge, even if you had the proper one in your warehouse stock, you would most likely still waste an hour labor for a tech to stop what he is doing and go across the street to get the required parts.

An accurate bill of material, along with a comprehensive scope of work and a project drawing can help you to realize maximum profits on each project.

Power Supplies – Linear vs. Switching

We have had questions from our customers about the differences in Linear and Switching power supplies. What are they and which do I want to use.

The basic function of an AC to DC power supply is to convert the incoming AC power supplied by the power company into DC output.  This is called rectifying.  It also transforms the voltage to the desired output voltage level.  In order to achieve usable current, it also must regulate and filter the output so that it remains constant under load and consistent regardless of the conditions at the input.

There are two technology approaches for achieving this –linear or switching technology.

Switching power supplies are the most common and popular power supplies in the access control realm.  They achieve the voltage step down by switching on and off very rapidly. They use a low-current, high voltage bridge rectifier to transfer power from the input side to the output side.  This allows the power supply to operate with less heat and to be made of lighter materials. As a result they are less expensive and weigh less.

However, the switching technology has some drawbacks.  These can create interference, referred to as noise and ripple, in several ways.

One way is by operating in a frequency similar to a contactless card reader, which can impact the readers’ ability of the reader to interact with the card.  In another, the magnetic field created from the on/off switching of a poorly designed power supply may induce voltage onto nearby wires through inductive coupling.  The electromagnetic field itself may cause electromagnetic interference (EMI) or radio frequency interference (RFI), which can impact the performance of audio equipment or technology that relies on RF communication.

This will show up at the reader as reduced read range (having to scrub the card on the reader), rejected reads or “phantom” access attempts.

A well-designed switching power supply with good regulation and filtering can greatly reduce the interference.  The power supply may cost a little more, but the result will be better when used with RF and proximity devices

Linear power supplies achieve the desired output voltage by getting rid of the excess power through resistors.  They transfer energy from the input side to the output side via circuitry called a linear bridge. 

Because they eliminate excess power through resistance, they can generate a lot of heat and are less efficient.  Because of the larger heat sink and heavier core materials needed to support the energy transfer, linear power supplies usually weigh more and usually cost more because of the types of material required.

But because they the always “on” there are no fluctuating magnetic fields and the voltage is steady, so no EMI or RFI.  This is why manufacturers of certain equipment require or recommend linear power supplies for use with their devices.