On eBay Now...

HP Model 423A Crystal Detector For Sale

When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

---

HP Model 423A Crystal Detector :
$65.00

HP 423A crystal detector model 423A. Please feel free to return items that do not meet your needs within the 30 day period, we only want satisfied customers! Thanks and God bless!

\"But seek first the kingdom of God and his righteousness, and all these things will be added to you.\" Matthew 6:33

---

---

---

HP Frequency Standard Model 103AR Quartz Oscillator

$250.00

---

Hewlett Packard HP Model 200CD Wide Range Audio Oscillator

$69.99

---

Canarm - Exhaust Shutter Fan 24in. 3,800/4,700 CFM 1/2 HP Model# XFS24

$325.00

---

Popular Tutorials

Alarms and Indicator Circuit diagrams

• Power supply failure alarm
• Theft preventer alarm
• Rain Alarm
• A simple electronic buzzer
• Water Level Indicator with alarm

Audio electronic circuits list

• Stereo Channel Selector
• Low cost intercom using transistors
• Infrared Head Phones
• Use the CD-ROM drive as a audio CD player without the computer
• Audio Visual Indicator for Telephones
• Ultrasonic pest repellent

Circuits for Cars/Motorcycles

• Charge Monitor for 12V lead acid battery.
• Wiper Speed Control
• Dome Light Dimmer for Cars
• Car anti theft wireless alarm.

Computer/PC Hardware Circuits :

• Control electrical appliances using PC
• Simple Analog to Digital Converter
• PC based Frequency Meter
• 7 segment rolling display using PC

Design Ideas :

• Soft ON/OFF switch

Fun/Games Circuits :

• Electronic Scoring Game
• JAM(Just A Minute) Circuit
• Flashy Christmas Lights
• TV remote control blocker

Signal/Sequence/Misc. Generators :

• Simple IF Signal Generator

Home/Garden related Circuits :

• Ultrasonic Pest Repeller
• Programmable Digital Code Lock
• Pot plant water tester

Lights & LED Circuits :

• Light Flasher (blinking lights)
• Automatic Dual output Display
• Emergency Light
• Automatic Room Lights
• Running Message Display

Motor Circuits :

• Automatic Speed Controller for fans & Coolers
• Soft Button type Motor Direction Controller
• Super simple stepper motor controller
• Discrete component motor direction controller

Music related Circuits :

• Digital Volume Control
• 5 band graphic equalizer

< Oscillator Circuits :

• Simple variable frequency oscillator
• Sawtooth wave generator

Power Supply (PS) Circuit diagrams :

• Negative supply from single positive supply
• Self switching Power Supply
• Ultra low drop linear voltage regulator

Radio,transmitter,receiver circuits :

• Car anti theft wireless alarm.
• Long range FM transmitter
• Remote control using VHF modules
• 40 meter Direct Conversion Receiver

Remote Control Circuit diagrams :

• Remote control using VHF modules
• Remote control using telephone
• A simple Remote control Tester
• Clap Activated Remote
• Radio Remote Control using DTMF
• Ultrasonic switch

Robotics related Circuits :

• Magnetic proximity sensors
• Color Sensor
• Super simple stepper motor controller

Sensors :

• Magnetic proximity sensors
• Dew sensor
• Color Sensor
• Metal Detector
• Optical toggle switch using a single Chip

Telephone Circuit diagrams :

• Telephone Ringer using 556 dual timers
• Two line intercom plus a telephone changeover switch
• Telephone line based audio muting and light on circuit
• Having secrecy in parallel telephones
• Telephone call meter using calculator & COB

Test & Measurement Circuits :

• High Resistance Voltmeter
• A simple Remote control Tester
• Contactless Mains Voltage Indicator
• Zener Diode Tester