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Next Month in Silicon Chip Getting Started with the Micromite, Part Four The final instalment in the series covers features such as power saving, using touch-sensitive screens, non-volatile memory, interrupt routines and other features. Using a DDS Module for AM Radio IF Alignment Advertising Index Altronics........................... INSERT Blamey Saunders hears.............. 5 In this article, we present updated software and slight tweaks to the hardware of the Micromite BackPack Touchsreen DDS Signal Generator described in the April issue. These changes make it a cinch to align the IF stage of a transistor or valvebased superheretodyne AM radio. Dave Thompson...................... 111 Arduino-based Digital LC Meter Hare & Forbes....................... OBC A fully operational digital inductance and capacitance meter made from a standard Arduino board, I2C LCD, prototyping board, comparator IC, reed relay and a handful of small components. Measures capacitance from 0.1pF to over 2.7µF and inductance from about 10nH to over 100mH, with five-digit resolution. Note: these features are prepared or are in preparation for publication and barring unforeseen circumstances, will be in the next issue. The June 2017 issue is due on sale in newsagents by Thursday May 25th. Expect postal delivery of subscription copies in Australia between May 25th and June 12th. Notes & Errata SC200 Audio Amplifier, January-March 2017: in the circuit diagram, Fig.1 on pages 30 & 31 of the January 2017 issue, D3 and D4 are shown connected across the pre-fuse ±57V rails when they are actually connected across the collectors of Q11-Q16, ie, after the fuses. Also, in the PCB overlay diagrams (Fig.4) on page 80 of the February 2017 issue, the pairs of 100W resistors on either side of VR1 should be 220W to match the circuit and parts list, and there is a 330W resistor not shown immediately above VR2 which should be fitted (see adjacent photo). All these errors have been corrected in the online version of these issues. High Power DC Motor Speed Controller. February 2017: on page 67 under the heading Testing the second paragraph should read: "Rotate VR2 and VR3 fully clockwise and VR1, VR4, VR5 and VR6 fully anticlockwise. Set VR7 mid way". The difference is VR1 is rotated anticlockwise and VR2 clockwise, while VR7 is set mid way. GPS Analog Clock Driver, February 2017: two bugs in the software have been brought to our attention. One only affected the stepping version and caused a weak clock motor drive as the three paralleled outputs didn't always provide the same polarity output. This is fixed with revised firmware (v2.6). The other affected all versions of the clock but only when using certain GPS modules (eg, VK16HX) and would result in a failure to acquire GPS time even if the module had a proper satellite lock. This has also been fixed in v2.6 firmware for stepping hands and v1.3 for sweep hands. Touchscreen Precision Voltage/Current Reference, October & December 2016: there is a discrepancy between the circuit diagram, PCB overlay and parts list. The circuit diagram shows 22kW & 750W feedback resistors for REG1, which is correct, but the PCB overlay and parts list show these as 56kW and 1.5kW respectively. The 56kW/1.5kW combination could result in damage to REG1 when the circuit is powered up. If you have purchased a kit, contact us and we will send the correct resistors and if you request it, a replacement CS5173 regulator IC. Otherwise, use the 22kW and 750W values as shown in the circuit diagram, Fig.2 on pages 76 and 77 of the October 2016 issue. High-Current Adaptor for Scopes & DMMs, August 2012: one 3.3MW resistor has been omitted from the parts list. The Altronics terminal barrier code P2103 mentioned has the wrong pin pitch; use Jaycar HM3162 instead. Finally, note that on page 75, the article says that IC1 and IC2 have the same number of pins but this is not correct; IC1 has 14 pins and IC2 has 16 pins. 112  Silicon Chip Digi-Key Electronics.................... 3 Emona Instruments................. IBC Jaycar ........................... IFC,53-60 Keith Rippon Kit Assembly...... 111 Keysight Technologies...... INSERT LD Electronics......................... 111 LEDsales................................. 111 Master Instruments..................... 9 Microchip Technology................ 13 Mouser Electronics...................... 7 Ocean Controls......................... 15 PCB Cart................................... 11 Sesame Electronics................ 111 SC Online Shop..........29,108-109 SC Radio & Hobbies DVD....... 106 Silicon Chip Binders.................. 64 Silicon Chip PCBs..................... 83 Silicon Chip Subscriptions......... 67 Silicon Chip Wallchart............... 80 Silvertone Electronics................ 14 Tronixlabs................................ 111 Vintage Radio Repairs............ 111 Ask SILICON CHIP . . . continued from page 111 energy as heat. Since it's inside REG1's feedback loop, during normal operation, it has no real effect on circuit behaviour other than REG1's output voltage needing to be slightly higher than the voltage across the battery during charging, due to the voltage drop because of the current flowing through R1. We hope this helps in your underSC standing of the circuit. siliconchip.com.au