Fan controlled by humidity sensor

I have a problem with machine tools getting condensation on them when conditions in the shed read dew point.

A possible solution being explored is to circulate air with a fan, possible inducting outside air, when humidity approaches condensing conditions.

A quick search reveals the HDS10 resistive humidity sensor for a dollar or so on eBay.

Above is the HDS10 humidity sensor.

Most low cost humidity sensors use a humidity dependent capacitive element, the HDS10 is different in being a humidity dependent capacitive element and is therefore simpler to use with microcontrollers with ADC input.

HDS10-02

The above graph is from the datasheet. It is intended primarily for sensing high humidity (dew point, condensing conditions) which suits this application.
Continue reading Fan controlled by humidity sensor

U-BLOX LEA-6T GPS module – for experiments

This article documents a LEA-6T module build for general experiments.

The LEA-6T is an inexpensive GPS module (~$40 at time of purchase, but getting cheaper) that can supply raw pseudo range data.

LEA-6T02

The module above is supplied for use on UAVs of various kinds, and came complete with a plastic radome and cables to suit an APM copter. The module also contains a 3D compass (magnetometer) which is not used here.

LEA-6T03

Above is the internals of the module with a custom cable to pick up just the RS232-TTL signals from the GPS (and supply 5V). The connector is a 8pin Hirose DF13. Continue reading U-BLOX LEA-6T GPS module – for experiments

Atten APS3005S – a better thermostatic fan control

The Atten APS3005S is a 0-30V 5A linear DC power supply.

Atten-hcctl00

This later model includes a thermostatically controlled fan which at moderately light currents short cycles (10s on 20s off) and is very annoying… especially since it sits above my desk.

This project describes application of the generic heating / cooling controller (hcctl) to control the fan, reducing the short cycling nuisance.
Continue reading Atten APS3005S – a better thermostatic fan control

Micro SD card premature failure

I bought a couple of ‘generic’ micro SD cards on eBay about a year ago. They were not much cheaper than brand name cards, and though only speed 6 rated, were available locally for quick delivery. I have a vague recollection that it might have been a RPi product supplied with NOOBS on it (I have a couple of SD adapters with the RPi logo on them).

IMG_1599

These were both used in RPi B systems and worked without fault for the last year, though they are not running full time (perhaps a couple of hundred hours of use).

During a Raspbian sofware update, both cards failed with the same problem, they effectively became read-only cards. Continue reading Micro SD card premature failure

Chinese counterfeiters at it again – EZP2013

Some while ago I purchased a EZP2013 device programmer on eBay.

EZO2013

There were literally scores of sellers, and they all looked the same, and some variation in price from about US$25 to US$50… which is not unusual.

I used the thing a few times, and it was clearly a very poor product so I replaced it with a SOFI SP-8B which cost close to US$50 on Aliexpress including a bunch of (6) adapters. Continue reading Chinese counterfeiters at it again – EZP2013

UV cure adhesive for temperature sensors

Seeing the promotion of a clear adhesive with cure initiated by ~400nm UV light from a LED source, one’s mind wondered to its application for attaching temperature sensors to heatsinks etc.

A sample of Kafuter K-300 was tested.

UvDiodeTestAbove is the test jig, a 1N4004 diode is attached to the corner of a scrap of 1.6mm thick aluminium sheet using the adhesive which was cured with UV light and then allowed 10 hours further to strengthen (if that helps). Continue reading UV cure adhesive for temperature sensors

Arduino app to set DS1307 Real Time Clocks.

I use a number of implementations of the DS1307 or DS3231 Real Time Clock chip, preferably the latter these days as they are considerably more accurate and compatible with DS1307 code.

In some applications, it is necessary or sometimes just better to preset the clock before connecting it into the application, and the need arises to set the clock ‘stand alone’. The method I have used for this has been clumsy and not as accurate as one might want for the DS3231, so this article describes a new solution.

IMG_1563

The solution uses an Arduino as the engine if you like. Above is an Arduino Pro, but a range of similar Arduinos would be equally suitable. ALso pictured are three RTCs, one connected to pins A2, A3, A4 and A5 providing GND, VCC, SDA and CLK respectively. Continue reading Arduino app to set DS1307 Real Time Clocks.

MultiStar 5200mAh 3S Lipo – initial tests

This article documents initial tests on a MultiStar 5200mAh 3S Lipo.

Two of these were purchased for about A$24 ea + delivery from the HK Australian warehouse.

On delivery, the batteries were served a balance charge to full capacity.

MultiStar52003SAbove, one of the batteries with the usual mods to suit my quadcopters. A heavy heatshrink encapsulation to reduce the risk of battery damage from crashes and flying propeller bits, rocks etc. A little velcro path to help stabilise the battery on the quad, a ‘gripper’ for the balance plug, balance plug secured to keep it out of the props, and a charge indicator for convenience.
Continue reading MultiStar 5200mAh 3S Lipo – initial tests

Fox flasher MkII – high power 2 LED solar powered beacon

Fox flasher MkII – owenduffy.net described an animal deterrent based on an STC 8051 microcontroller and running from a single LiPo cell.

This article describes a further development using a solar cell, shunt regulator, 1S LiPo cell with protection board, and two high power red LEDs.

FF100Above, the unit constructed in a medium size Jiffy box, and a 6V 0.6W PV panel fixed to the top with silicone adhesive. The LDR is fixed to one end with silicone adhesive.

Two SM 1W red LEDs are fitted to opposite sides. They are 120° LEDs, the holes are countersunk to provide for light dispersion and the LEDs clamped to the inside with small brass brackets and heat sink rubber, a little silicone adhesive seals the holes. Continue reading Fox flasher MkII – high power 2 LED solar powered beacon

PIK

This article describes a build of the PIC Iambic Keyer (PIK).

Screenshot - 18_04_16 , 19_47_22

Above is the generic circuit diagram of the PIK.

This one runs on 4.5V from 3 x AA cells. A 3000mAh battery will run it in ‘sleep’ mode for around 2,000,000 hours or 230 years… the shelf life of the batteries determines their useful life and there is consequently no ON/OFF switch.

So, the variation to the circuit above is that the zener regulator circuit is not required, Z1 is omitted and R5 is replaced by a 50mA Polyfuse. C3 is 0.0068µF to give a range of 6-36WPM on 4.5V.

PIK201

Above, the internals. The electronics is assembled on a small piece of Veroboard with jacks at the rear for paddle, hand key and output, a pot for speed control and switches for TUNE and AutoSpace.

PIK202

Above is the external view of the keyer prior to labelling.