Flatter terrain compared to last week - easier to keep up the pace on the whole course.
A stupid mistake that cost maybe 2 minutes on #1 - otherwise mostly OK orienteering.
Firmaliiga result 24./58
First firmaliiga event this fall. Overall very physically demanding with most controls placed high up on hills/cliffs.
#1 a bit of circling before finding the right control
#2 ok and safe route, but slow
#3-#4-#5 OK
#6 very long leg with one or two big hills in the way. A route-choice with more running along the road might have been better.
#8 I tried to plan a good route to this control on the way to #6, but other runners and poor judgement caused extra minutes wasted here also.
Firmaliiga result 45./59
OK orienteering but not that fast running. Warm weather and hilly terrain. Maybe a bit surprisingly the big detour from 4->16 using roads and paths worked out OK since it was my second best split-time in terms of placing.
I've been assembling and testing this PCB over the past few days:
It's a linear +/-2 A voltage-to-current amplifier meant for driving a constant current through a Thermoelectric Cooler (TEC). The circuit is (loosely) based on a 2001 Burr-Brown/TI application note "SBEA001 - Optoelectronics Circuit Collection".
Description: U1 drives one half of the H-bridge (Q1 and Q3) based on a feedback signal which is the amplified (U3) voltage drop across a current-sensing resistor (R4). The other H-bridge half (Q2 and Q4) is driven by an inverting amplifier (U2) which forces the other end of the TEC symmetrically, inverted, to follow the output from U1.
Here's how these things look on the PCB:
After some assembly, bugfixing, and tweaking I measured a DC transfer function like this:
I am happy with the small offset of <0.2 mA and the linearity seems good. There is a rather large gain-error since the design-goal was 200 mA/V and the measured sensitivity is 179 mA/V. The AC frequency response is quite ugly with a high peak at a few kHz. In the time-domain this shows up as severe ringing when driven by a square-wave input. (aside: the SBEA001 application note shows a SPICE-simulated frequency response up to MHz frequencies - theory/simulation and practice differ a lot in this case!).
Things learned so far:
If all goes well this TEC-drive will be part of a temperature control system consisting of about five different PCBs or circuits:
Another 100k ride, this time from west to east. Warm but breezy weather. Only one short stop to refill two water-bottles and eat an energy-gel.
Last 100k in 4h 17min (23.3 km/h)
Total 110k in 5h 2min.
Here's a plot of the time error between the standard unix system-time, kept on time using NTP, and a much more accurate PTP-server based on White Rabbit that runs on a fancy FPGA-based network-card.
Note that without NTP a typical computer clock will be off by 10 ppm (parts-per-million) or more. This particular one measured about 40 ppm error in free-running mode (no NTP). That means during the duration of this 16e4 s measurement we'd be off by about 640 milliseconds (way off the chart) without NTP. With NTP the error seems to stay within 3 milliseconds or so. The offset of -16 milliseconds is not that accurately measured and could be caused by a number of things.
A lot of slow thicket areas and a map which I found difficult to read. Many paths that were visible in terrain were not on the map - while the ones drawn on the map were overgrown and hard to find. A similar story with large stones where I thought many were missing from the map.
First longer bike ride this year.
To avoid the midday heat I started in the evening around 18:00 and finished late around 23:00 with barely enough light to ride. There is a nice newly built bike-path between espoonlahti and kirkkonummi.
Problems on two out of the eleven controls yesterday. These also show up as the worst placings in the split times.
The #3-#4 (17-18 on the map) leg should have been a straightforward run along paths. However I took a short-cut from the path too soon and crossed about 1/3rd of the leg through the woods. Then right inside the control circle I ran past the control almost to the road south of it before returning. The blue line shows the path I should have taken.
On the very last control (14 on the map) it would have been clearly faster to return to the road (green line) and not go straighter through the light-green (thick) area.