StrobeMaker v1.42

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Background

This program is used make custom high quality strobes for checking the speed of a turntable. The program can output the strobe to either the printer or to a BMP file for further processing.

How to install

Simply copy the StrobeMaker.exe to a folder of your choice and create a shortcut to the exe-file. To uninstall, delete StrobeMaker.exe.

Download StrobeMaker

How to use

Select the wanted speed and frequency in "Strobe type" combo-boxes. The standard options for 16, 33, 45 and 78 rpm are present, as well as a custom option and a combined 33.3 and 45 rmp option. The "Custom" option allows numbers between 10 rpm and 500 rpm to be entered. The "Custom no of bands" generates a strobe with the entered number of bands.

After selecting the speed and frequency, a sample strobe is drawn on the screen. Note, this drawing is not to scale! If a strobe for the exact speed is not possible, the program will draw a "gap strobe" (see below).

Use the "Print..." button to select a printer and, if needed, select the quality/resolution using the "Properties" button in the printer dialog. A higher resolution will result in a higher quality strobe. Also, the strobe will fill the full printable width (or height - which ever is smaller) of the paper, so if using a big printer make sure you select an "A4" or "Letter" paper size. Print and cut out the resulting strobe - cut the spindle hole carefully with a sharp knife.

Use the "Save..." button to save to a BMP file - the program will ask you for a name and then save the file as a 4096x4096 pixel BMP file.

Place the strobe over the spindle of the turntable, start the turntable at the speed corresponding to the strobe (on automatic turntables, make sure only the platter is started and that the arm isn't moved onto the platter). Use a standard tungsten bulb (energy saving lamps and fluorescent lamps can't be used) and adjust the turntable speed until the strobe band is steady and does not move in either direction. If the band moves clockwise, the turntable is running to fast and if it runs counter-clockwise, the turntable is to slow.

If it wasn't possible to generate an exact strobe, a "gap strobe" has been made: With gap strobe the lines will be stationary when the speed is correct, but once every turn all the lines will "jump" (this is where the gap is) and then the lines will be stationary again.

Alternatively, you can generate a "dual ring strobe": For a dual ring strobe, you use the two bands on the strobe to estimate a approximate correct speed. The "Actual speed" lines can help you make a more precise speed setting, e.g. 45 rpm at 50 Hz will generate a band of 45.113 rpm and one of 44.776 rpm: The 45.113 rpm band is 0.113 rpm to fast and the 44.776 is 0.224 rpm to slow, which means the 45.113 band should move slowly anti-clockwise (as 45 rpm is slower than 45.113) and the 44.776 band should run 2 times as fast (0.224 is approximately 2*0.113) clockwise.

How to adjust the speed of the turntable

Some turntables has speed adjustment on the plith on the form of two knobs or, in some case, be inserting a screew driver in the corresponding adjustment hole. Some turntables (B&O comes to mind) can be adjusted either under the platter or by opening the turntable. In this case, you should really consider having a proffesional make the adjustment.

Other turntables, like older Lenco's and Thorens, has the speed adjustment build into the speed selection in some form.

Finally, some turntable appears to have no option of adjustment. Some common examples of this are Linn's, Rega's, Project's etc. where the speed selection is by manually moving the belt on the motor pulley. In these case the speed can be changed by changing the diameter of either the motor pulley or the subplatter or platter where the belt drives the main platter by taking away material or adding material.

A better solution is to build the TTPSU construction, which enables adjustment of 2 phase AC motors (as used on MOST of the turntables mentioned above and on many other - even some with a knob or lever for changing speed) and also makes it possible to change speed with out moving the belt.

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