Black Star Apollo 100 frequency counter


I saw this old Apollo 100 Universal Counter Timer. However, the B channel does not work apparently. This is clearly a fairly common issue, as another chap was also looking for a solution and/or service manual, Black Star Apollo Frequency Counter, back in 2014.

This is probably due to the reduced input of channel B and blown input stage (front end)

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Banana splitz


For bench supplies or for patch cables (for synths or otherwise), banana leads are most useful and banana plugs are quick and easy to wire up. They are also very easy to make yourself so there’s no need to buy ready made cables.

Banana leads are commonly use in audiophile setups as speaker cables due to their high current rating and low resistance.

Banana plugs come in a variety of styles. However, some plugs are unsheathed and so, when stacked, leave the connections unprotected and open to the air (which could result in accidental shorts) while some don’t.

They come in 2 or 4 mm diameters.

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Dual rail 12 volt supply from 24 volt SMPS


After seeing this 24 V SMPS on eBay, Protek 24V 8.4A 200W SMPSU Switch Mode Power Supply Medical Grade PSU PM200-14C, I thought it would be initially useful for a 24 V 3D printer. Then I thought it would be handy for a ±12 V supply for a synth… man, the possibilities are freaking endless..!

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Build your own frequency meter ATtiny2313


Following on from Frequency Abacuses, from Re: Ten Dollar Frequency Counter’s – Thread #2, there is a link, Schaltungsbeschreibung ‘reziproker Frequenzzähler 0,0025Hz-50MHz’, to building your own frequency meter:

Do any of these come with a simple serial port output of the reading? With let’s say a 1 per second dump at 9600 baud?
That would be immensely more useful than a display, really.

Are you able to programm an ATtiny2313? If yes you can use ‘’ to get a frequency counter 0,005 Hz – 1 MHz (up to 200 MHz with prescaler). With 20 MHz Xtal baudrate is 38400. The LCD is not necessary at all.

You can find another low frequency counter using Arduino UNO board with serial data output. First version 0,016 Hz – 250 kHz and 2. version with internal prescaler up to 7 MHz:

A simple 5-digit counter is shown here:

Sorry for german description.

Below is the German translation… and the ATtiny2313 version is at the bottom of the page.

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