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Mart

Lakeside Motor Focuser - Temperature Sensor

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I have three OTAs in my Obsy each with a motorised focuser but only one focuser control unit. I just swap the cable from the controller to the focuser motor on whichever OTA I'm using for imaging.

I'm now "upgrading" to run two cameras to double my image capturing whenever there's a gap in the clouds. So I need two focuser control units.

I've started a build of Robert Brown's DIY controller - just waiting for the bare PCB to be delivered from China.

I have a Lakeside focuser motor connected to one of the OTAs which has the standard Robofocus motor wiring on pins 1-5 of the DSub - but it also has a temperature sensor which looks to be connected to the pins 6-8.

Does anyone know what type of sensor is on the Lakeside units and what the pinout connections are across the pins 6-8?

If possible I thought I'd use this temperature sensor to do the focus compensation.

  

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If you've ordered the board from Aisler.Net (Germany based) then they usually only take a few days to come.... 

As for the temperature probe, I use variants of these DS18B20's e.g.https://www.ebay.co.uk/itm/DS18B20-Waterproof-Digital-Sensor-Thermal-Probe-Temperature-Thermometer-Arduino/111431573979?epid=1386221694&hash=item19f1d6e1db:g:ekwAAOSwxH1T5i~D They are simple 3 wire probes, which I wire up using 'stereo' headphone plugs & chassis sockets... 

 

 

 

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The temperature probes in my Lakeside focusers are a DS1820 1-Wire sensor. It has 9 bit temperature resolution. This device is now discontinued, so getting one can be problematic. A drop in replacement is the DS18S20 which is a 'doctored' version of the now common DS18B20. 

The DS18B20 has programmable 9 to 12 bit resolution and defaults at 12 bits. The DS18S20 is effectively a DS18B20 fixed at 9 bit resolution.

DS18B20 Datasheet

DS18S20 Datasheet

Application notes describing the differences between the devices.

If you search online for a DS1820 datasheet you get directed to the DS18S20 datasheet. Externally they function identically, though internally they are different. I can upload an actual DS1820 datasheet if you wish.

I made an Arduino based dual focuser for 2 Lakeside focusers and can switch between using 9 bit data if connected to the Lakeside DS1820 temperature probe, or 12 bit data if connected to a separate DS18B20.

The Lakeside D9 connections are pin 6 = Gnd, pin 7 = data, pin 8 = +5V. All three devices mentioned here have the same pinout.

The latest Lakeside focus units may well have DS18S20 temp probes installed. I bought mine several years ago, which used DS1820 devices.

Hope that helps. :smile:

Alan 

Edited by symmetal

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Just be aware, that there are many bad copies of the DS18B\S20 series of devices. To ensure you get pukka ones you need to buy from a reliable distributor, i.e. RS Components, Farnell etc.... 

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