电子制作天地网站欢迎您的光临,欢迎提出宝贵意见或建议。本站信息产业部备案: 粤ICP备05114582号
植物缺水告警器
water alarm for plant

时间:2007-12-31 7:05:41 来源:未知 作者:未知 编辑: 【关闭


植物缺水告警器,water alarm for plant

关键字:缺水告警电路

 
Parts:
R1___________470K1/4W Resistor 
R2_____________3K3 1/4W Resistor
R3___________100K 1/2W Trimmer Cermet
C1_____________1nF 63V Polyester Capacitor
C2____________47µF 25V Electrolytic Capacitor
D1__________1N4148 75V 150mA Diode
D2_____________5mm. Red LED
IC1___________4093 Quad 2 input Schmitt NAND Gate IC
P1,P2_______Probes (See text)
SW1___________SPST Slider Switch
B1______________3V Battery (2 AA 1.5V Cells in series)


Device purpose:

This circuit is intended to signal when a plant is needing water. A LED illuminates at maximum brightness when the ground in the flower-pot is too dry: it dims gradually as the water's content in the pot grows, turning off when the optimum moisture's level is reached. This condition is obtained trimming R3.

Circuit operation:

IC1D forms a square wave oscillator with approx. 10/90 mark-space ratio. It feeds the output probe P1 and its signal, inverted by IC1A is compared with that picked-up by P2 in the NAND gates IC1B & IC1C in parallel, driving the LED. When a low resistance exists between the probes, due to an high water's content in the flower-pot, the LED is off, turning gradually on as the resistance between the probes increases.

Notes:

  • A square wave is used to avoid probes' oxidization.
  • Probes can be long nails, carbon rods obtained from disassembled exhausted 1.5V batteries, or even a couple of screwdrivers.
  • The probes must be driven in the pot's ground a few inches apart.
  • Due to 3V supply, the LED needs not a limiting resistor.
  • Power consumption: LED off = 50µA; LED full on = 1mA.
  • To switch-off the circuit, you can short the probes. In this case SW1 can be omitted.
  • Using an high-efficiency LED, brightness variations are better emphasized. In this case a limiting resistor could be necessary.

上一篇: 水位告警器 下一篇:下雨告知器

◆相关文章◆
◆ 编辑推荐 ◆
用户:
更多评论
您要为您所发的言论的后果负责,故请各位遵纪守法并注意语言文明。60个字以内
留言:
验证码:

免责声明:
●本站所有内容均来自网络,以学习为目的,如果侵犯了您的利益,请来信告知,立即删除,站长邮件为"diy+dzdiy.com",请将"+"变更为"@"
●电子制作存在风险,请注意人身安全,如果您在根据本站电路进行制作过程中发生伤害,本站不负任何责任。

版权所有:www.dzdiy.com ? 2001-2019 本站信息产业部备案: 粤ICP备05114582号