AK-380 preamp out adding
Recently I have bought a very cool small chiness stereo amplifier called AK-380. It has a Bluetooth, USB and SD card multimedia imputes and also an digital FM tuner (without RDS) and a line in ( you can choose from 3.5 jack or RCA but the line in is one).
The output has very clear sound as it was rated as AB class amplifier with bass, treble and volume potentiometers on the front panel. Not the last – the price was great for such functions in one unit. The built quality is excellent , aluminum and very good quality plastic. It looks not cheap but professional.
Classical scheme of intercom system
Together with doorbells almost every building consisting of more than one floor there is built an intercom system. Currently the market offers advanced digital intercom systems in which electronic occupies a significant part. Each company offers its products and respectively provides diagrams and installation schemes.
Кey elements of which are built a classical intercom installation are carbon microphone (M) electro dynamic speaker (T) and power supply. This is one of the first circuits created and serves more to explain the principle of design of the intercom, but is fully operational.
Upon impact of sound pressure (speech) on the carbon microphone diaphragm (1) , it begins to vibrate In synchrony with these vibrations the clamping force of the carbonaceous grains (2) are changing , thereby changing the electrical resistance between the electrodes (3) and (4). When constant voltage U0 ( in the case 8V) is applied, the current through the microphone also is changing. If the microphone is incorporated into the primary coil of the transformer Tr , then in the ends of the secondary coil an AC voltage occurs , the shape of which corresponds to the sound pressure acting on the diaphragm of the carbon microphone.
Classic scheme of installation of door bell
Doorbells serve to signal the presence of a guest at the front door. In essence they are the most diverse – with mechanical bell melodic bells (e), wireless bells (e), etc. Here will be shown on a classical scheme such installation to which may be added and electron components. For example, to be replaced conventional electro-mechanical bells with electronic ones that have a variety of tunes.
Doorbells of an apartment consists of a bell placed in the entrance hall, two buttons – the front door of the apartment building (a boutonniere) and the front door of the apartment, connecting wires.
Power supply of doorbells for the entire building is performed by a general bell transformer. His classical performance is shown in Fig. 1. , the primary side is 220V/1A, the secondary side is with medium conclusion and accordingly 3V, 5V and 8V and power of 4VA. It is installed in the main switchboard at the entrance.
Wires are twisted pair of solid copper wire with insulation – PVU-A1-wire, insulation color blue and black. The temperature of the application it should not be less than -5 ° C. Section of the core is 0.5 – 0.75 mm ², the minimum bending radius is 10xD (for 0,5 mm ² D = 4,6 mm) the wires are as many as the number of apartments plus two. Both wires are common to all buttons respectively and all the bells. Installation of wires is hidden in the pipes through floors and junction boxes to buttons and bells for each apartment.
Standards for terminating of RJ45 connectors.
When network devices have being connected some cables are used terminated by RJ 45 connectors. All cables used in building of Structured Cabling Systems no matter of construction or category have four twisted pair colored in different way.
1 pair white/blue-blue;
2 pair white/orange-orange;
3 pair white/green-green;
4 pair white/brown-brown;
Incoming search terms:
T586b, rj45 standard b, .
Design of building TV (Cable and SAT) networks
Design of CATV and SAT TV
1.Cabel colective television systems ( CATV ) – Satellite television signal have recived by central equipment (recivers) after that it have been modulated in frequency range from 40 to 862 MHz . To transmite signals for fisical laeyr is used coax cabel 75 Ohms.
Design of Structured Cabling Systems
Categories/Classes in SCS
1.Cooper phisical layer– shielded and unshielded.
- Category 3/Class “C”
- Category 5е/Class “D+”
- Category 6/Class “E”
- Category 7/Class “F”
TIA and ISO comaprison of frequences, categories and classes are shown in the next tabel: Tabel 1.
| Tabel 1: TIA and ISO clasification according to frequency bandwidth | ||||
|---|---|---|---|---|
| Frequency Bandwidth | TIA (Components) | TIA (Cabling) | ISO (Components) | ISO (Cabling) |
| 1 – 100 MHz | Category 5e | Category 5e | Category 5e | Class D |
| 1 – 250 MHz | Category 6 | Category 6 | Category 6 | Class E |
| 1 – 500 MHz | Category 6A | Category 6A | Category 6A | Class EA |
| 1 – 600 MHz | n/s | n/s | Category 7 | Class F |
| 1 – 1,000 MHz | n/s | n/s | Category 7A | Class FA |
Incoming search terms:
Design of Security Alarm systems
Modern security system allowed to be conected to user and security centers through wireless, phone lines and Ethernet. Capabilities for setup of user rights, reley contacts (outs) for control, RJ45 out and software to connect with WEB interface, using proxy readers and tags. Extension with RS485 moduls for additional zones and releys.
Design of :
1.Security systems for residentials(haouse and appartments) and administartive buildings(offices)
- Control panels.
- Key pads.
- Active Infra Red Detectors(IRD).
- Passive digital and analogues IRD.
- Accoustic detectors .
- Magnetic contacts.
- Seismic detectors.
- outside and inside sirens.
2.Perimeter security systems
- Infra red bariers.
- Micro-wafe bariers.
Design of Fire Alarm systems
Design of fire alarms with international standards and Bulgarian regulations. There are two main fire alarn control panels:
1.Analogue addressabel control panel.
2.Conventional control panel
Elements of fire alarms:
- Photoelecrics smoke detectors.
- Photoelecrics heat detectors.
- Reflective Beam detectors.
- Door indicators.
- Menual fire butons.
- Sirens –outside and inside.
Design of Access control systems
Design of Access Control instalations (AC): Modern access control sysytem can managed and control from a fue doors to tausands of doors. The management of local resources is efficient and real-time. Systems have big card / user capacity and event buffer . Full access input/output functions (incl. exit, door monitoring, alarm output etc.). They have a lot of netowork intefacec including 10/100 Ethernet , RS232 and RS485. Administrative control over working hours, time and attendance, punctuality, official absences, holidays, sick-leaves, etc. as well as individual control over hours worked.
Design of CCTV
Design of CCTV (Closed Circuit TeleVision): modern surveillance systems can be divaided on two major tips:
1.Ethernet based systems – IP cameras and video servers (DVRs) using SCS (Structured Cabling Systems) for phisical layer to trasmit video over Ethernet frame and protocols TCP , UDP , HTTP , DHCP и др. Managment and setup from PC through WEB interface and software. High quality of recording. Mounting in 19″ standard telecommunication rack.
2.Clasic coaxial based systems – Cameras with TV out, multiplexers, quads, switchers, time laps recorders and etc.
Usefully: Dependence between lens size and distanse to observe Lens.