James Long, Ph.D., P.E. Retired Analog and RF Consulting Engineer
Product and Store Reviews
This is a list of my personal experience with products and stores.
Here are the results of my good and bad experiences. Hopefully this will keep you from making the same purchasing mistakes I have made.
Montblanc Writing Instruments
Montblanc has a long history of manufacturing fountain pens and a short one of pencils, roller ball pens, and ball point pens. The relative times are reflected in the product functionality. They are made from thin plastic that breaks and scratches easily. For $25 to $30 Montblanc will refurbish them. The models with removable caps frequently have a poor fit when the cap is placed on the other end of the pen which makes them fall off and break. [Since writing this they have gone through a George Orwell 1984 memory hole routine with their lifetime warranty that they claim does not exist and never did while I remember taking advantage of it at least once. They also claim that they are exempt from the requirements of state consumer protection laws. The Bethlehem PA Better Business Bureau agrees with them. Adolph Hitler will be proud of both of them.]
Fountain Pens These are generally well made. One problem is their being used mostly in cold climates. You may have to store the pen in a point upward position and carry it in a way that insulates it from your body heat. Otherwise, the ink will evaporate and recondense just where your fingers go while writing.
Mechanical Pencils These are a total flop in many ways. The 0.9 mm size grabs the lead so poorly that as you write a flat is formed on the lead and when you rotate the pencil, the lead rotates back with the flat down. This makes the lines very broad and light in color. The 0.5 and 0.7 mm sizes grab the lead better, but advance it in a fixed length increment. The 0.5 mm lead is not strong enough to withstand the leverage against it during writing and frequently breaks off. This leaves the 0.7 mm which works even partially to my liking. It takes a bit of practice to develop the one handed dexterity to advance the lead. The two handed method is more sure, but cumbersome.
Rollerball Pens These are generally well made. The problem is the extremely high price for replacement inserts. Several companies make refills for the smaller pen which drives down prices. The larger pen only has extravagantly expensive refills only made by Montblanc and warehoused by suppliers so long that they are almost dried out by the time you buy one.
Ballpoint Pens These are generally well made. The problem is the extremely high price for replacement inserts. Several companies make refills for the smaller pen which drives down prices. The larger pen only has extravagantly expensive refills only made by Montblanc and warehoused by suppliers so long that they are almost dried out by the time you buy one.
suggestions Rotring is better for the money.
J&R Music and Computer World
This store has multiple tier prices. They also have errors of description in their catalogs. If you give them the reference number of your catalog, you will not get their lowest prices.
HP/Agilent 33120A Function Generator
This generator has the front panel controls as an afterthought. Many of the functional controls cannot be made from the front panel in real time, or at all. These are mostly changing the parameters of the modulating waveform. If all you want to do is have an unmodulated signal or one modulated by a sine wave, you are in luck. If you want rectangular or triangular modulation, you are out of luck.
The amplitude will drop to zero for a significant fraction of a second as you rotate the knob and sweep the frequency through certain frequencies.
This product is not designed by Agilent, it uses a chip from another manufacturer. I suggest that you look into the Wavetek arbitrary generators.
Artech House Books, IEEE Press, and CRC Press
These publishers once only reprinted old classics. This meant that everything they sold was first-class. Recently, they have begun to publish books newly written. These fall into three categories. The first is abstract mathematicians who slant their mathematical work towards engineering in hopes to increase their sales. The second is people who manage engineers or are society officials. These people rarely have any engineering experience. Their books are pretty much mindlessly copying the contents of their file cabinets into book form.
If you want design knowledge, look for the rare third category, authors who are practicing engineers who have produced saleable products. Then thumb through the book and read paragraphs at random to see if the information content suits your needs. Are the equations explained and related to the real world design decisions you will have to make?
Tektronix TDS700 and 3000 Family of Digital Storage Oscilloscope
700 series This family of oscilloscopes work as well and intuitively as a Tektronix analog oscilloscope. The sampling is in real time. The triggering can be on pulses that are too wide or too narrow. Most clients I show mine to go out and buy one for themselves. There are two problems with it. The first is that it insists on undersampling a narrow band signal and aliasing it to a much lower frequency before taking measurements on it. A 1 MHz signal's frequency was measured at 1.1 Hz. The second problem is inherent in sampling. If you slow the sweep on a high frequency signal to observe any low frequency modulation, the sampling rate is reduced and you get a low frequency aliased version of the signal. Another problem is the 1% full scale self noise. This occurs on all vertical scale factors. The shape is the same on all sweep widths.
3000 series. This scope is easy to use because the controls are the same as on analog oscilloscopes. It has the same self noise problem as the 700 series, only smaller. The noise is 0.5 mV on the 1 mV/div range and is two pixels peak to peak on the higher ranges. This noise is independent of amplifier bandwidth and sweep rate. There is an averaging mode where the self noise can be reduced. This is good for looking at ringing on signals, but averages the system under test noise to zero as well.
In summary, these two scopes are good for most uses, but keep your old analog scope for solving noise problems in circuits.
This service has several problems that all stem from shortage of capital. They fall into technical and business problems.
Technical Problems include spotty service in supposed service areas. Many areas of the country without service, and getting a try again later signal when you try to make a call.
Business Problems include long waits for customer service, undisclosed and increasing fees, and having to pay for an instrument that does not work with other providers should you choose to go with a new PCS provider.
This company resells service from another company and donates 10% of your charges to a charity of your choice.
Here is the story of my experience with them. I usually overpay my utility bills so that I have an account credit for the utility to work from and therefore I do not have to send a payment in very frequently. I find this economically advantageous because of the low interest at banks and the postage and checking charges.
My first payment was three times the bill. The next month my invoice did not show a credit, but instead a new amount due. I did not send in a payment. The next month showed no credit or past due, but just a new amount due for that month's service. The subsequent invoices showed no past due or credit, but just a new amount due for that month's service. I kept track of my account and sent in enough every three months to continuously have a net credit. I wrote them to inquire but got no replies. I tried phoning them and got no answer. I wrote a letter offering to complain to their state attorney general if they continued to stonewall me. Finally, I got a phone call and the person claimed that I was totally uneducated in accounting software and had no grounds to complain about their flawlessly perfect software. Furthermore, they were going to stop my long distance service because I rarely paid my invoice.
I had also written The American Family Association which received my 10% donation plus $1000 a year from me directly to ask their assistance in the matter. They never responded and so lost my donations forever after. I did write the Oklahoma Attorney General about the matter, and they got in contact with Americom. Americom claimed that I had not only failed to pay my bills, but also sent abusive FAX messages to them. Since I am a business, I had archived all of my itemized long distance bills and copied them and sent them to the Attorney General along with an reconstructed account. These showed two thing, the first being that my account was always in the credit and the second being that I had made only two phone (or FAX) calls to anywhere in the state of Oklahoma and those two were to the Attorney General.
The final result was that Americom refunded my final account balance, but did not give an apology for the false, slanderous statement about me made to the Attorney General or reinstate my long distance service.
X-10 Security System
This system, sold by Radio Shack and others, is an illustration of the saying, "Hay is cheaper after passing through the horse."
Wall switch modules are improperly heat sunk and fail consistently every two or three years. They fail sooner if used on 100 W or larger bulbs.
Sirens do not automatically cut off after a fixed time. They go indefinitely, even when you are on a few month's vacation, to the annoyance of the neighbors.
False alarms are frequent because the radio links use on-off keying and the system sounds the alarms when it fails to get a error free transmission from a sensor three times in a row. This occurs every few years as the batteries go low or the transmissions from two sensors overlap.
Automatic, random resetting of the remote control ID numbers so that when you go to enter the building, you cannot disarm the system until you enter, trigger the alarm, and unplug the system.
Defects in the remote controls so that when you try to disarm the system, the alarm commands the panic mode to sound the sirens and you cannot turn them off with the remote.
Lucent Technology Digital Telephone Answering Machines
This company operates open loop. Some of the problems below have been around for decades. You wonder if Lucent tests the products before marketing them.
Stored voice quality is a hit or miss thing with their compression algorithm. The voice parameters of women in distress are not recorded legibly so that if the wife calls from an emergency, the husband will not get the information to respond or help.
The remote control codes do not function as described in the literature or intuitively. For instance, if you want to review a message more than twice, you have to hang up and phone again. If you want to listen to an old message, you have to first listen to the new messages.
The automatic clock setting feature is not well thought out. It occurs at midnight while DST comes and goes at 0200. Two days a year the time is off by one hour. This will wreck havoc with your timed recording if you don't plan ahead.
You pay much more for what you could have gotten from the public library. I was charged $45+ for a ten sheet copy of a magazine article.
At one time this was a good operation. They have degenerated into another Radio Shack junk store. Most of their problems are in the area of dishonesty and reliability.
One example. Their photo of a desk weather station shows the LCD display with sharp contrast when photographed from a high angle as you would view it on your desk. The actual device has a washed out screen from that angle. You have to look up at it at a 45 degree angle to get a high contrast display.
They have an electrostatic air filter. Their first model had a 50% chance of becoming broken within a year (after the warranty expired.) The new model at least lasts a few years. The advertising for both of these is totally false. They give comparative energy consumption figures against some filter that would keep a public theater clean. The most recent model contains UV lamp to generate ozone for killing germs. In the back page of the manual there is a warning that ozone makes asthma worse and the UV lamp should be turned off in these cases. Asthmatics are the major customer for these things. Their claim of room size cleaned is way too big. The American Lung Association says that such filter should turn over the air in a room every 10 minutes. These devices probably would do it once per few hours.