Project: RC Voltmeter
@0810
Here’s the output from gerbv,
_gerbv.jpg)
This is my first time using gerbv, and I can see how valuable this tool is gonna be. I can already see a ‘ton’ o’ routing mistakes, but all that’ll be affected are a few bits of silkscreen text. It’s not the end of the world, but it’s nice to be able to learn something new everyday.
I’ve just calculated the costs involved, boards will be priced as follows:
Complete unit: £24.99
PCB + MCU: £19.99*
Intl. Shipping: £ 3.99 (Registered Airmail)*This includes the bare PCB and a fully programmed MCU.
LED colours as follows,
8 7 [RED] 6 5 4 [Orange] 3 2 1 [Yellow]
/* Bill of Materials */
01x 16f88, 18-Pin SOIC
08x 150R, 1206
01x 10K, 1206
01x 470R, 1206
01x 5K1, 1206
01x 1K, 1206
01x 1n4148
08x LEDs, 1206
…Cont
Before I forget, a list of component values,
- R1: 1K
- R2: 5K1
- R3: 10K
- R4: 470R
- R5 - R12: LED current*
The Voltage is Sensed via the two resistors, R1/R2, which form a potential divider. As a hump pack is rated at 6V, we want the output to be 5V, i.e. R2/(R1+R2) * 6 = 5V. The values defined above will set this accordingly, as it forms a 5/6 divider 
The LED Current is what defines the values for resistors R5 - R12, via the following formula,
Resistance = (5v - LED Forward Voltage)/0.02
Here we will be driving the LEDs @ 20mA, but since blue LEDs have an ~Vf = 3.3v, while white, red, orange and green have a ~Vf = 2.0 to 2.2v, it is fairly obvious that I shouldn’t define a set resistance here. That said, if you are completely unsure use 85-100R for BLUE LEDs and 150R for any other colour(s).
19.09.2006
This project started out as an idea and is now based here. This idea was based on the product by HPI, but this unit is always on and *could* potentially leave your hump pack empty if connected for extended periods.
At the same time I don’t enjoy having a fairly powerfull hump pack in my RC, just to have the juice sucked out of it by a simple visual aid, that won’t be looked at while the RC is running for sure!
.jpg)
Above is the first PCB design, which has been sent for fabrication.
- RC Voltmeter
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RC Voltmeter at bsodmike.com said,
September 19, 2006 @ 15:35
[...] Project: RC Voltmeter [...]